com.goldencode.p2j.persist.dialect

Class Dialect

java.lang.Object

com.goldencode.p2j.persist.dialect.Dialect

Direct Known Subclasses:

MariaDbLenientDialect, P2JH2Dialect, P2JPostgreSQLDialect, P2JSQLServer2008Dialect

public abstract class Dialect
extends java.lang.Object

Extends the API defined by Hibernate's abstract Dialect class to add methods required by the P2J persistence framework. The implementations of these methods are necessarily specific to the backing database and may be different for different database vendors.

NOTE: a longer term goal is to eliminate this interface by merging these methods back into the mainstream Hibernate Dialect class.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Dialect.WeightAggregator Helper interface for weights' aggregation

Field Summary

Fields

Modifier and Type	Field and Description
(package private) static java.lang.String	CASE_TYPE_TOK Token used to mark placeholder for varchar type when generating the DDL for creating a a varchar_casesensitive/varchar_ignorecase.
(package private) static int	DEFAULT_MAX_WIDTH The default MAX-WIDTH for character fields if the attribute is not specified.
private static java.util.Map<java.lang.String,Dialect>	dialectByJdbcType
private static java.util.Map<java.lang.String,Dialect>	knownDialects Map of known/loaded dialect instances
private static CentralLogger	log Logger
(package private) static java.lang.String	SCALE_TOK Token used to mark a placeholder for the scale when generating the DDL for creating/altering a decimal column in a table.

Constructor Summary

Constructors

Constructor and Description
Dialect()

Method Summary

Modifier and Type	Method and Description
void	activateErrorHandler(java.sql.Connection conn) Activate error handler at the database side.
abstract void	addRtrimmedExpression(java.lang.String expr, java.lang.StringBuilder sb) Composes a rtrim equivalent call for a specified expression.
boolean	allowBindParamsInRecursiveCTE() Check if bind parameters in recursive CTEs are supported.
boolean	allowDBUniqueCheck() Determine if the Dialect supports index validation (with the VALIDATE keyword).
boolean	allowSelectWildcard() Check if this dialect allows the selection of fields using * wildcard.
void	beforeDriverLoad() Set any database parameters before, to be available when the database driver is loaded.
abstract java.sql.Blob	blobCreator(java.sql.Connection conn, byte[] bytes) Create a Blob instance from the specified bytes.
abstract java.lang.String	buildRemoteURL(java.lang.String url, Database database) Build the URL to be used for a remote connection, based on the given URL and database.
java.lang.String	checkErrorFn() Get name of the checkError UDF.
void	checkIndexConstraints(P2JIndex p2JIndex, java.util.Map<java.lang.String,P2JField> fields) If the dialect has some constraints about the index size, do the calculations and report any possible error/warning when the database schema is set.
abstract java.sql.Clob	clobCreator(java.sql.Connection conn, java.lang.String value) Create a Clob instance from the specified value.
int	computeIndexKeySize(java.lang.Class<? extends BaseDataType> type, java.lang.Object val) Computes the size (in bytes) occupied by this value when stored as index-key in an index.
java.lang.Class<? extends com.mchange.v2.c3p0.AbstractConnectionCustomizer>	connectionCustomizer(DatabaseConfig cfg) Get c3p0 ConnectionCustomizer class for the dialect.
java.lang.String	containsUdfName() Return the name of the CONTAINS UDF
java.lang.Object	createContext(Persistence persistence) Create a data object, the purpose of which is specific to a particular dialect implementation, to be stored as a context-local object.
abstract SequenceHandler	createSequenceHandler(java.lang.String ldbName) Creates and returns a SequenceHandler for a database.
static java.util.Map<java.lang.String,Dialect>	dialects() Get known dialects by name
ErrorManager.ErrorEntry	errorEntry(java.lang.String message) Create the error descriptor from the SQLException message
abstract boolean	explicitSetCollation() Check if the dialect needs to set an explicit collation during schema DDL generation.
abstract java.lang.String	extractColumnName(java.lang.String expr) Given a column expression as queried from database metadata, extract the root name of a column.
abstract java.lang.String	formatDate(date d) Format a date object as a string which is appropriate for use in an SQL statement.
abstract void	generateWordTablesDDLImpl(java.lang.String dbName, java.io.PrintStream out, java.lang.String eoln, java.util.Collection<WordTable> wordTables) Worker method for generateTriggerDDLs().
java.lang.String	getAddForeignKeyConstraintString(java.lang.String table, java.lang.String fkName, java.lang.String fkFields, java.lang.String refTable, java.lang.String refFields, java.lang.String indent, java.lang.String eoln) Creates and returns a string which represent the alter table statement for adding a new foreign key constraint.
abstract java.lang.String	getAnalyzeString(java.lang.String table) Construct and return a string which represents the analyze or similar statements for this dialect.
java.lang.String	getCatalogPattern(Database database) Provides catalog matching pattern to load data correctly from JDBC.
java.lang.String	getCodepage(java.sql.Connection conn) Use the provided database connection to extract the codepage/CharSet used by the database and report it back to the caller.
java.lang.String	getCollation(java.sql.Connection conn) Use the provided database connection to extract the collation used by the database and report it back to the caller.
java.lang.String	getComputedColumnFormula(java.lang.String colName, boolean ignoreCase) Returns the formula for character computed columns.
java.lang.String	getComputedColumnPrefix(boolean caseSensitive) Get the prefix, if any, which should be prepended to computed column and/or property names.
java.lang.String	getComputedColumnString(java.lang.String name, java.lang.String type, int scale, boolean cs) Constructs and returns the declaration of a computed column based on its name, type, scale, and case-sensitiveness.
java.lang.String	getCreateIndexString(boolean unique) Returns the beginning of the DDL statement for creating an index.
java.lang.String	getCreateIndexString(boolean unique, boolean softUnique) Returns the beginning of the DDL statement for creating an index.
java.lang.String	getCreateIndexString(P2JIndex index, boolean unique, boolean toFile) Build the DDL to create an index based upon the specified definition.
abstract java.lang.String	getCreateSequenceString(java.lang.String name) Generate a DDL string which will create a global sequence.
java.lang.String	getCreateSequenceString(java.lang.String name, boolean isTemporary) Generate a DDL string which will create a global sequence.
abstract java.lang.String	getCreateSequenceString(java.lang.String name, long start) Generate a DDL string which will create a global sequence with the given starting value.
abstract java.lang.String	getCreateSequenceString(java.lang.String name, java.lang.Long init, java.lang.Long increment, java.lang.Long minVal, java.lang.Long maxVal, java.lang.Boolean cycle) Generate a DDL string which will create a sequence with given properties.
java.lang.String	getCreateTableString() Returns the beginning of the DDL statement for creating a permanent table.
abstract java.lang.String	getCreateTemporaryTablePostfix(boolean noUndo) Return the ending of the DDL statement that creates a temporary table.
abstract java.lang.String	getCreateTemporaryTableString(boolean ifNotExist) Return the beginning of the DDL statement that creates a temporary table.
java.util.List<java.lang.String>	getDatabasePrepareStatements(Database database) Get a list of database prepare DDL statements.
java.lang.Long	getDecimals(java.lang.String type, java.lang.String decimals, java.lang.String comment) Get decimals value for types that support it.
abstract java.lang.String	getDelimiter() Get the statement delimiter for this dialect.
static Dialect	getDialect(Database database) Get the instance of a concrete subclass of this class which is associated with the given database.
static Dialect	getDialect(Settings settings) Get the instance of a concrete subclass of this class, as specified in the given settings.
static Dialect	getDialect(java.lang.String jdbcType) Get the instance of a concrete subclass of this class which is associated with the given JDBC database type.
abstract java.lang.String	getDriverClassName() Get the name of the JDBC driver class associated with this dialect.
abstract java.lang.String	getDropIndexString(boolean ifExists, java.lang.String idxName, java.lang.String tableName) Obtain a DDL statement which drops a SQL index.
abstract java.lang.String	getDropIndexString(P2JIndex index) Build the DDL to drop an index based upon the specified definition.
abstract java.lang.String	getDropSequenceString(java.lang.String name) Generate a DDL string which will drop a sequence.
abstract java.lang.String	getDropTableString(boolean ifExists, java.lang.String tableName) Obtain a DDL statement which drops a SQL table.
java.sql.Date	getHighDate() Retrieve the latest possible date value which is valid for the backing database.
int	getIndexLengthLimit() Some dialects have constraints about the maximum size of fields that compose an index.
java.lang.String	getInvisibleSpecificator() Return a string which marks that a column is computed, so it should be marked as invisible to allow implicit skipping of it when using wildcard selection (*) or direct access.
abstract java.lang.String	getJdbcDatabaseType() Get the name of the JDBC database type (as in JBC URL).
java.lang.String	getLimitString(java.lang.String sql, int offset, int limit) Get the limit string for the given limit and offset.
java.sql.Date	getLowDate() Retrieve the earliest possible date value which is valid for the backing database.
int	getMaxEntriesInSelect() Returns the max numbers of fields selected that the dialect can allow without throwing an error.
int	getMaxParameterCount() Obtain the number of parameters a query of this dialect is allowed by the SQL server.
abstract java.lang.String	getProcessedCharacterColumnName(java.lang.String name, boolean ignoreCase) Adjust a character column name appropriate to this dialect, such that it can be inserted into an index.
java.lang.String	getSchemaPattern(Database database) Provides schema matching pattern to load data correctly from JDBC.
abstract ScriptRunner	getScriptRunner() Get a ScriptRunner instance for the dialect.
java.lang.String	getSequenceCurrValString() Generate the appropriate select statement to retrieve the current value of a sequence.
abstract java.lang.String	getSequenceCurrValString(java.lang.String sequenceName) Generate the appropriate select statement to retrieve the current value of a sequence.
abstract java.lang.String	getSequenceNextValString(java.lang.String sequenceName) Generate the appropriate select statement to retrieve the next value of a sequence.
abstract java.lang.String	getSequencePrefetchString(java.lang.String sequenceName) Generate the appropriate select statement to pre-fetch multiple, ascending values from a sequence.
abstract java.lang.String	getSequenceSetValString() Generate the appropriate select statement to reset the value of a sequence.
abstract java.lang.String	getSequenceSetValString(java.lang.String sequenceName) Generate the appropriate select statement to reset the value of a sequence.
abstract java.lang.String	getSequenceSetValString(java.lang.String sequenceName, long newVal) Generate the appropriate select statement to reset the value of a sequence.
java.lang.String	getSequenceSQL(Database database) Provides SQL to load sequences.
java.lang.String	getSpecificTypeAsString(FqlType type) Converts and return the specified FqlType to a string representation which can be used in a SQL query (cast or other construct).
java.lang.String	getSqlIndexName(P2JIndex index) Obtain the name of an index.
java.lang.String	getSqlMappedType(java.lang.Class<?> fwdType, int scale, java.lang.Boolean caseSensitive) Get the SQL mapping for a specific FWD data type.
java.lang.String	getSqlMappedType(java.lang.String fwdType, int scale, java.lang.Boolean caseSensitive) Get the SQL mapping for a specific FWD data type.
abstract int	getSyntheticIndexSize(boolean unique) Returns the size of the synthetic part of the index.
abstract boolean	hasFullSequenceSupport() Returns true if this dialect fully support the sequences as 4GL language (most important: bounded values, cycle).
abstract java.lang.String	id() Get dialect id.
java.lang.String	initErrorFn() Get name of the initError UDF.
abstract boolean	injectComputedColumns() Report whether the computed columns should be injected on table creating.
abstract void	inlineLimit(boolean on) Enable/disable limit clause inlining.
boolean	isAutoCi() Returns true if the dialect handles case-insensitive compare operations for case-insensitive character columns
boolean	isAutoRtrim() Returns true if the dialect handles automatically rtrimming for character columns.
abstract boolean	isCaseInsensitiveColumn(java.lang.String name) Report whether the given column name represents an alias or an expression which indicates the column is case insensitive.
boolean	isComputedColumn(java.lang.String name) Report whether the given column name represents an alias or an expression which indicates the column is computed.
abstract boolean	isConnectionError(java.lang.Exception exc) Given an exception, this method will check if it indicates a database connectivity error.
abstract boolean	isMetadataSortAsc(java.lang.String value) Check if the given value is a descending clause for a column index.
abstract boolean	isMetadataSortDesc(java.lang.String value) Check if the given value is an ascending clause for a column index.
abstract boolean	isNativeUDFsSupported() Check if native UDFs are supported for the dialect
abstract boolean	isQueryRangeParameterInlined() Indicate whether a query parameter which is part of a range check should be inlined into the where clause, or whether it should be substituted into a prepared statement.
boolean	isUdfContains(java.lang.String name) Check if the provided name is the name of the CONTAINS UDF
boolean	isUdfOriginatedError(java.sql.SQLException e) Check if the exception was caused by an error in UDF.
boolean	isUdfOriginatedWarning(java.sql.SQLException e) Check if the exception was caused by a warning in UDF.
abstract boolean	isUniqueConstraintViolation(java.sql.SQLException sqle) Checks if the SQLState of the SQLException matches the dialect specific UNIQUE_VIOLATION code.
abstract boolean	needsComputedColumns() Indicate whether this dialect requires computed columns to participate within index definitions, instead of embedded expressions.
int	orderByNulls(java.lang.StringBuilder sb, java.lang.String expression, java.lang.String field, boolean asc, boolean forceAsc) Determine if the sort component or index needs to be augmented with a NULLS FIRST/LAST option and add the required expression(s) as needed by this dialect.
void	postTransaction(Persistence persistence, java.lang.Object context, boolean rollback) A dialect-specific callback hook which is invoked by the persistence runtime framework after a transaction is complete.
boolean	preferDisjunctiveForm() Returns true if the dialect handles the optimization of an augmented construct which is resulted from comparing exactly two character fields.
abstract java.lang.String	prepareMetadataParameter(java.lang.String param) Prepare the given metadata query parameter.
void	preparePermanentDatabase(Database db) Prepare the specified database by creating all necessary function aliases and setting global parameters.
abstract java.lang.String	processMetadataResult(java.lang.String value) Process the given metadata query result.
java.lang.String	quote(java.lang.String expr) Apply dialect-specific quoting.
abstract boolean	requiresExplicitCastInsideTernary() Determines whether substitution parameters should be explicitly casted to their datatypes inside "then ? else ?" statement.
void	resetErrorHandler(java.sql.Connection conn) Reset error handler at the database side.
boolean	resolveBooleanConstant(java.lang.String text) Resolve the given text to a boolean value.
abstract ScriptSplitter	scriptSplitter() Get the splitter for DDL scripts.
abstract boolean	supportsBooleanDatatype() Indicates whether this dialect supports boolean datatype.
abstract boolean	supportsFunctionOverloading() Indicate whether this dialect natively supports the overloading of user defined functions by parameter number and data type.
boolean	supportsLazyQueryResultsMode() Determine if the Dialect supports queries executed in a lazy manner.
boolean	supportsVariableLimit() Indicate whether a variable limit is supported by this dialect.
ParmType	translateToParmType(java.lang.String type, java.lang.String comment) Translation from database column type to ParmType.
java.lang.String	udfSchema() Get UDF schema name (if applicable).
boolean	useCTE4Contains() Check if Common Table Expressions should be used for converted CONTAINS operator
boolean	useMixedNode4Contains() Check if mixed mode re-write should be used for converted CONTAINS operator
boolean	useNullEquality() Returns true if the dialect handles null equality.
abstract boolean	useUdf4Contains() Check if UDF should be used for converted CONTAINS operator
abstract boolean	useWordTables() Check if word tables should be used for converted CONTAINS operator
java.util.Optional<Dialect.WeightAggregator>	weightAggregator() Get the WeightAggregator instance for the dialect if defined

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SCALE_TOK

static final java.lang.String SCALE_TOK

Token used to mark a placeholder for the scale when generating the DDL for creating/altering a decimal column in a table.

See Also:

Constant Field Values

CASE_TYPE_TOK

static final java.lang.String CASE_TYPE_TOK

Token used to mark placeholder for varchar type when generating the DDL for creating a a varchar_casesensitive/varchar_ignorecase. This is strictly for H2.

See Also:

Constant Field Values

DEFAULT_MAX_WIDTH

static final int DEFAULT_MAX_WIDTH

The default MAX-WIDTH for character fields if the attribute is not specified.

See Also:

Constant Field Values

log

private static final CentralLogger log

Logger

knownDialects

private static final java.util.Map<java.lang.String,Dialect> knownDialects

Map of known/loaded dialect instances

dialectByJdbcType

private static final java.util.Map<java.lang.String,Dialect> dialectByJdbcType

Constructor Detail

Dialect

public Dialect()

Method Detail

getDialect

public static Dialect getDialect(java.lang.String jdbcType)

Get the instance of a concrete subclass of this class which is associated with the given JDBC database type.

Parameters:

jdbcType - Database jdbc type.

Returns:

Instance associated with the given jdbcType

getDialect

public static Dialect getDialect(Database database)

Get the instance of a concrete subclass of this class which is associated with the given database.

There is one instance per subclass type; they are stateless and shared.

Parameters:

database - Database identifier.

Returns:

Instance associated with the given database, or null if no dialect has been configured for the database.

dialects

public static java.util.Map<java.lang.String,Dialect> dialects()

Get known dialects by name

Returns:

known dialects by name

getDialect

public static Dialect getDialect(Settings settings)

Get the instance of a concrete subclass of this class, as specified in the given settings. If the settings do not specify a dialect class, null is returned.

There is one instance per subclass type; they are stateless and shared.

Parameters:

settings - Settings object which should contain a dialect entry.

Returns:

Instance of a concrete dialect subclass, if specified in the given settings; otherwise null.

scriptSplitter

public abstract ScriptSplitter scriptSplitter()

Get the splitter for DDL scripts.

Returns:

the splitter for DDL scripts

getScriptRunner

public abstract ScriptRunner getScriptRunner()

Get a ScriptRunner instance for the dialect.

Returns:

a ScriptRunner instance for the dialect.

blobCreator

public abstract java.sql.Blob blobCreator(java.sql.Connection conn,
                                          byte[] bytes)

Create a Blob instance from the specified bytes.

Parameters:

conn - The JDBC connection.

bytes - The blob data.

Returns:

The blob instance.

clobCreator

public abstract java.sql.Clob clobCreator(java.sql.Connection conn,
                                          java.lang.String value)

Create a Clob instance from the specified value.

Parameters:

conn - The JDBC connection.

value - The clob data.

Returns:

The clob instance.

getDriverClassName

public abstract java.lang.String getDriverClassName()

Get the name of the JDBC driver class associated with this dialect.

Returns:

Fully qualified driver class name.

getJdbcDatabaseType

public abstract java.lang.String getJdbcDatabaseType()

Get the name of the JDBC database type (as in JBC URL).

Returns:

The name of the JDBC database type.

id

public abstract java.lang.String id()

Get dialect id.

Returns:

dialect id

useUdf4Contains

public abstract boolean useUdf4Contains()

Check if UDF should be used for converted CONTAINS operator

Returns:

true if UDF should be used for converted CONTAINS operator

useWordTables

public abstract boolean useWordTables()

Check if word tables should be used for converted CONTAINS operator

Returns:

true if tables should be used for converted CONTAINS operator

isNativeUDFsSupported

public abstract boolean isNativeUDFsSupported()

Check if native UDFs are supported for the dialect

Returns:

true if native UDFs are supported for the dialect

udfSchema

public java.lang.String udfSchema()

Get UDF schema name (if applicable).

Returns:

UDF schema name (if applicable).

checkErrorFn

public java.lang.String checkErrorFn()

Get name of the checkError UDF.

Returns:

the name of the checkError UDF.

initErrorFn

public java.lang.String initErrorFn()

Get name of the initError UDF.

Returns:

the name of the initError UDF.

isUdfOriginatedError

public boolean isUdfOriginatedError(java.sql.SQLException e)

Check if the exception was caused by an error in UDF.

Parameters:

e - the exception in question

Returns:

true if the exception was caused by error in UDF.

isUdfOriginatedWarning

public boolean isUdfOriginatedWarning(java.sql.SQLException e)

Check if the exception was caused by a warning in UDF.

Parameters:

e - the exception in question

Returns:

true if the exception was caused by error in UDF.

errorEntry

public ErrorManager.ErrorEntry errorEntry(java.lang.String message)

Create the error descriptor from the SQLException message

Parameters:

message - SQLException message

Returns:

error descriptor.

useCTE4Contains

public boolean useCTE4Contains()

Check if Common Table Expressions should be used for converted CONTAINS operator

Returns:

true if Common Table Expressions should be used for converted CONTAINS operator

useMixedNode4Contains

public boolean useMixedNode4Contains()

Check if mixed mode re-write should be used for converted CONTAINS operator

Returns:

true if mixed mode re-write should be used

isUdfContains

public boolean isUdfContains(java.lang.String name)

Check if the provided name is the name of the CONTAINS UDF

Parameters:

name - name to be checked

Returns:

true if the provided name is the name of the CONTAINS UDF

containsUdfName

public java.lang.String containsUdfName()

Return the name of the CONTAINS UDF

Returns:

the name of the CONTAINS UDF

connectionCustomizer

public java.lang.Class<? extends com.mchange.v2.c3p0.AbstractConnectionCustomizer> connectionCustomizer(DatabaseConfig cfg)

Get c3p0 ConnectionCustomizer class for the dialect.

Parameters:

cfg - Database configuration.

Returns:

c3p0 ConnectionCustomizer class for the dialect.

activateErrorHandler

public void activateErrorHandler(java.sql.Connection conn)
                          throws java.sql.SQLException

Activate error handler at the database side.

Parameters:

conn - Database connection

Throws:

java.sql.SQLException - on error.

resetErrorHandler

public void resetErrorHandler(java.sql.Connection conn)
                       throws java.sql.SQLException

Reset error handler at the database side.

Parameters:

conn - Database connection

Throws:

java.sql.SQLException - on error.

generateWordTablesDDLImpl

public abstract void generateWordTablesDDLImpl(java.lang.String dbName,
                                               java.io.PrintStream out,
                                               java.lang.String eoln,
                                               java.util.Collection<WordTable> wordTables)

Worker method for generateTriggerDDLs(). It generates the DDLs needed to create all triggers in a database with a specific schema and using a certain dialect.

Parameters:

dbName - The target schema.

out - The PrintStream used for output.

eoln - OS-specific end of line terminator.

wordTables - word tables by name

createContext

public java.lang.Object createContext(Persistence persistence)

Create a data object, the purpose of which is specific to a particular dialect implementation, to be stored as a context-local object. This allows a dialect to establish context-local data which is stored by the persistence runtime framework, without the overhead of a separate, context-local variable. This object will be handed back to the dialect in callback methods when the services of certain hooks are required.

Since the context-local data is specific to a particular dialect implementation, it is optional. Dialect implementations which do not have a need for this data should simply return null.

Parameters:

persistence - Provider of persistence services.

Returns:

Dialect-specific, context-local data, or null.

postTransaction

public void postTransaction(Persistence persistence,
                            java.lang.Object context,
                            boolean rollback)
                     throws PersistenceException

A dialect-specific callback hook which is invoked by the persistence runtime framework after a transaction is complete.

Default implementation does nothing.

Parameters:

persistence - Provider of persistence services.

context - Optional, context-local data created previously by createContext(com.goldencode.p2j.persist.Persistence).

rollback - true if transaction ended with a rollback; false if transaction ended with a commit.

Throws:

PersistenceException - if any persistence-related error occurs.

getLowDate

public java.sql.Date getLowDate()

Retrieve the earliest possible date value which is valid for the backing database.

Returns:

Earliest date supported by the backing database or null to indicate no particular restriction.

getHighDate

public java.sql.Date getHighDate()

Retrieve the latest possible date value which is valid for the backing database.

Returns:

Latest date supported by the backing database or null to indicate no particular restriction.

formatDate

public abstract java.lang.String formatDate(date d)

Format a date object as a string which is appropriate for use in an SQL statement.

Parameters:

d - Date to be formatted as a string.

Returns:

Formatted representation of the given date.

extractColumnName

public abstract java.lang.String extractColumnName(java.lang.String expr)

Given a column expression as queried from database metadata, extract the root name of a column. For example, a column name as found within an index in metadata might be represented as:

    upper(rtrim("key"::text))
 

We are interested only in the key root name, so we strip away the upper() and rtrim() functions, the double quotes, and the ::text suffix.

Parameters:

expr - Expression containing column name as natively represented by the database dialect.

Returns:

Root column name.

getProcessedCharacterColumnName

public abstract java.lang.String getProcessedCharacterColumnName(java.lang.String name,
                                                                 boolean ignoreCase)

Adjust a character column name appropriate to this dialect, such that it can be inserted into an index. This may involve wrapping it within one or more functions, prepending a special prefix to designate a computed column, or any other transformation appropriate to the database syntax.

Parameters:

name - Base column name.

ignoreCase - true to cause case to be ignored, else false.

Returns:

Processed column name.

isCaseInsensitiveColumn

public abstract boolean isCaseInsensitiveColumn(java.lang.String name)

Report whether the given column name represents an alias or an expression which indicates the column is case insensitive. Assume the column represented by name is already determined to be the appropriate data type for textual data.

Parameters:

name - Column name, alias, or expression.

Returns:

true if name represents case-insensitive data.

isComputedColumn

public boolean isComputedColumn(java.lang.String name)

Report whether the given column name represents an alias or an expression which indicates the column is computed. Assume the column represented by name is already determined to be the appropriate data type for textual data.

Parameters:

name - Column name, alias, or expression.

Returns:

true if name represents a computed column. Default implementation returns false.

needsComputedColumns

public abstract boolean needsComputedColumns()

Indicate whether this dialect requires computed columns to participate within index definitions, instead of embedded expressions.

Returns:

true to indicate computed columns are required; false if the backing database can embed an expression within an index definition.

getComputedColumnPrefix

public java.lang.String getComputedColumnPrefix(boolean caseSensitive)

Get the prefix, if any, which should be prepended to computed column and/or property names.

Parameters:

caseSensitive - true if this is a character field was declared with CASE-SENSITIVE attribute. In each case the column name will be name-decorated differently.

Returns:

Computed column/property prefix, or an empty string if the backing database does not use computed columns.

See Also:

needsComputedColumns()

supportsFunctionOverloading

public abstract boolean supportsFunctionOverloading()

Indicate whether this dialect natively supports the overloading of user defined functions by parameter number and data type.

Returns:

true if the backing database natively supports overloading, else false.

supportsBooleanDatatype

public abstract boolean supportsBooleanDatatype()

Indicates whether this dialect supports boolean datatype. Support includes:

• usage of true and false literals;
• operations with boolean values;
• allowing functions to have booleans as parameters and return datatype.

Returns:

true if the above mentioned items are supported or false if they are handled by a replacement datatype (integer).

getCreateSequenceString

public abstract java.lang.String getCreateSequenceString(java.lang.String name)

Generate a DDL string which will create a global sequence.

Parameters:

name - Sequence name.

Returns:

Dialect-specific string to create the sequence, or null if not supported.

getCreateSequenceString

public java.lang.String getCreateSequenceString(java.lang.String name,
                                                boolean isTemporary)

Generate a DDL string which will create a global sequence.

Parameters:

name - Sequence name.

isTemporary - If the sequence should be temporary or not.

Returns:

Dialect-specific string to create the sequence, or null if not supported.

getCreateSequenceString

public abstract java.lang.String getCreateSequenceString(java.lang.String name,
                                                         long start)

Generate a DDL string which will create a global sequence with the given starting value.

Parameters:

name - Sequence name.

start - Sequence starting value.

Returns:

Dialect-specific string to create the sequence, or null if not supported.

getCreateSequenceString

public abstract java.lang.String getCreateSequenceString(java.lang.String name,
                                                         java.lang.Long init,
                                                         java.lang.Long increment,
                                                         java.lang.Long minVal,
                                                         java.lang.Long maxVal,
                                                         java.lang.Boolean cycle)

Generate a DDL string which will create a sequence with given properties.

Parameters:

name - Sequence name. Mandatory not null.

init - Sequence starting value. Mandatory not null.

increment - Sequence incrementing value. Mandatory not null.

minVal - Sequence minimum value. Optional.

maxVal - Sequence maximum value. Optional.

cycle - Sequence cycling property. Optional, if missing assumed not cycling.

Returns:

Dialect-specific string to create the sequence, or null if not supported.

getDropSequenceString

public abstract java.lang.String getDropSequenceString(java.lang.String name)

Generate a DDL string which will drop a sequence.

Parameters:

name - The name of the sequence to be dropped.

Returns:

Dialect-specific string to drop the sequence, or null if not supported.

getSequenceSetValString

public abstract java.lang.String getSequenceSetValString(java.lang.String sequenceName,
                                                         long newVal)

Generate the appropriate select statement to reset the value of a sequence.

Parameters:

sequenceName - The name of the sequence.

newVal - The new value to be set.

Returns:

Dialect-specific string to set the current value of the sequence, or null if not supported.

getSequenceSetValString

public abstract java.lang.String getSequenceSetValString(java.lang.String sequenceName)

Generate the appropriate select statement to reset the value of a sequence.

Parameters:

sequenceName - The name of the sequence.

Returns:

Dialect-specific string to set the current value of the sequence, or null if not supported.

getSequenceSetValString

public abstract java.lang.String getSequenceSetValString()

Generate the appropriate select statement to reset the value of a sequence.

Returns:

Dialect-specific string to set the current value of the sequence, or null if not supported.

getSequenceNextValString

public abstract java.lang.String getSequenceNextValString(java.lang.String sequenceName)

Generate the appropriate select statement to retrieve the next value of a sequence.

Parameters:

sequenceName - The name of the sequence to be queried.

Returns:

Dialect-specific string to query the sequence, or null if not supported.

getSequenceCurrValString

public abstract java.lang.String getSequenceCurrValString(java.lang.String sequenceName)

Generate the appropriate select statement to retrieve the current value of a sequence.

Parameters:

sequenceName - The name of the sequence to be queried.

Returns:

Dialect-specific string to query the sequence, or null if not supported.

getSequenceCurrValString

public java.lang.String getSequenceCurrValString()

Generate the appropriate select statement to retrieve the current value of a sequence.

Returns:

Dialect-specific string to query the sequence, or null if not supported.

hasFullSequenceSupport

public abstract boolean hasFullSequenceSupport()

Returns true if this dialect fully support the sequences as 4GL language (most important: bounded values, cycle). If not fully supported, additional code is needed in P2J sequence class implementation to fix this.

Returns:

true if this dialect fully support 4GL sequences

getSequencePrefetchString

public abstract java.lang.String getSequencePrefetchString(java.lang.String sequenceName)

Generate the appropriate select statement to pre-fetch multiple, ascending values from a sequence. The values need not be contiguous.

Parameters:

sequenceName - The name of the sequence from which the values are to be retrieved.

Returns:

Dialect-specific SQL expression, or null if this feature is not supported by the dialect.

isConnectionError

public abstract boolean isConnectionError(java.lang.Exception exc)

Given an exception, this method will check if it indicates a database connectivity error.

Parameters:

exc - The exception to be checked.

Returns:

true if the exception indicates a database connectivity error.

isQueryRangeParameterInlined

public abstract boolean isQueryRangeParameterInlined()

Indicate whether a query parameter which is part of a range check should be inlined into the where clause, or whether it should be substituted into a prepared statement. This will result in an "inlined" substitution parameter within a where clause. For example, given a where clause of:

    where value ≥ ? and id = ?
 

along with respective substitution parameters of 45 and 100, the inlined version would read:

    where value ≥ 45 and id = ?
 

Only the id substitution parameter of 100 would be substituted into the prepared statement.

Inlining in such a way can give some database dialects the opportunity to choose a better query plan, than if the parameter being tested with a range check were to be substituted at statement execution time.

Note: this serves as a hint which may be overridden by runtime logic or other configuration settings.

Returns:

true to inline range check parameters; false to use normal parameter substitution.

inlineLimit

public abstract void inlineLimit(boolean on)

Enable/disable limit clause inlining. Inlining the limit clause will cause the limit/max value to be hard-coded into the SQL statement, rather than being bound as a substitution parameter.

Dialects are free to treat this method as a hint.

Parameters:

on - true to enable inlining; false to disable it.

requiresExplicitCastInsideTernary

public abstract boolean requiresExplicitCastInsideTernary()

Determines whether substitution parameters should be explicitly casted to their datatypes inside "then ? else ?" statement.

Returns:

true if they should be casted.

allowBindParamsInRecursiveCTE

public boolean allowBindParamsInRecursiveCTE()

Check if bind parameters in recursive CTEs are supported.

Returns:

true if bind parameters in recursive CTEs are supported.

getLimitString

public java.lang.String getLimitString(java.lang.String sql,
                                       int offset,
                                       int limit)

Get the limit string for the given limit and offset.

Parameters:

sql - Base select statement SQL without the limit/offset clause.

offset - Starting offset.

limit - Number of records to return.

Returns:

SQL with limit/offset clause appended.

supportsVariableLimit

public boolean supportsVariableLimit()

Indicate whether a variable limit is supported by this dialect.

Returns:

false; should be overridden by dialects which support a variable (i.e., not inlined) limit string.

resolveBooleanConstant

public boolean resolveBooleanConstant(java.lang.String text)

Resolve the given text to a boolean value. By default, if text matches the strings "true" or "1" case-insensitively, the result is true. Subclasses with more esoteric mappings may override this method.

Parameters:

text - A potential representation of a boolean constant.

Returns:

true if the given constant string represents boolean true, else false.

getDropIndexString

public abstract java.lang.String getDropIndexString(P2JIndex index)

Build the DDL to drop an index based upon the specified definition. The SQL is generated by using the database-specific dialect.

Parameters:

index - Definition of the index to be dropped.

Returns:

The DDL to drop the given index.

getCreateIndexString

public java.lang.String getCreateIndexString(P2JIndex index,
                                             boolean unique,
                                             boolean toFile)

Build the DDL to create an index based upon the specified definition. The SQL is generated by using a database-specific dialect.

It is expected that this method is NOT used at runtime, as it has a dependency on conversion project configuration being available.

Parameters:

index - Definition of the index to be created.

unique - If true, create the index as a unique index, otherwise omit the unique constraint.

toFile - true if the string will be output to a file. Otherwise it will be directly submitted via JDBC. TODO: this parameter seems to be unused. Drop it?

Returns:

The DDL which was created.

isAutoRtrim

public boolean isAutoRtrim()

Returns true if the dialect handles automatically rtrimming for character columns.

Returns:

as described above.

useNullEquality

public boolean useNullEquality()

Returns true if the dialect handles null equality. This is visible when doing null == null, which logically should return true, but not all dialects support this condition.

Returns:

true if the dialect permits null equality.

isAutoCi

public boolean isAutoCi()

Returns true if the dialect handles case-insensitive compare operations for case-insensitive character columns

Returns:

as described above.

preferDisjunctiveForm

public boolean preferDisjunctiveForm()

Returns true if the dialect handles the optimization of an augmented construct which is resulted from comparing exactly two character fields.

Returns:

as described above.

getComputedColumnFormula

public java.lang.String getComputedColumnFormula(java.lang.String colName,
                                                 boolean ignoreCase)

Returns the formula for character computed columns. This will be called in two cases: when generating the ddl for permanent databases schema (this will be written to a .sql file) and when creating temp-tables (the code will be sent directly to SQL).

Parameters:

colName - The base column name.

ignoreCase - true if this is a char field which has the "ignore case" flag set.

Returns:

The formula for computed columns or null if the dialect does not support computed columns.

getInvisibleSpecificator

public java.lang.String getInvisibleSpecificator()

Return a string which marks that a column is computed, so it should be marked as invisible to allow implicit skipping of it when using wildcard selection (*) or direct access.

Returns:

An SQL string specificator for invisible columns. null means that no such specificator is supported.

prepareMetadataParameter

public abstract java.lang.String prepareMetadataParameter(java.lang.String param)

Prepare the given metadata query parameter.

Parameters:

param - The metadata query parameter.

Returns:

the prepared parameter.

processMetadataResult

public abstract java.lang.String processMetadataResult(java.lang.String value)

Process the given metadata query result.

Parameters:

value - The metadata query result.

Returns:

the processed result.

isMetadataSortDesc

public abstract boolean isMetadataSortDesc(java.lang.String value)

Check if the given value is an ascending clause for a column index.

Parameters:

value - The value to be checked.

Returns:

true if the value is the "ascending" clause.

isMetadataSortAsc

public abstract boolean isMetadataSortAsc(java.lang.String value)

Check if the given value is a descending clause for a column index.

Parameters:

value - The value to be checked.

Returns:

true if the value is the "descending" clause.

getDatabasePrepareStatements

public java.util.List<java.lang.String> getDatabasePrepareStatements(Database database)

Get a list of database prepare DDL statements.

Parameters:

database - The database which needs to be prepared.

Returns:

The statement list.

explicitSetCollation

public abstract boolean explicitSetCollation()

Check if the dialect needs to set an explicit collation during schema DDL generation.

Returns:

true if the collation needs to be explicitly set.

getDelimiter

public abstract java.lang.String getDelimiter()

Get the statement delimiter for this dialect.

Returns:

the statement delimiter.

beforeDriverLoad

public void beforeDriverLoad()

Set any database parameters before, to be available when the database driver is loaded.

buildRemoteURL

public abstract java.lang.String buildRemoteURL(java.lang.String url,
                                                Database database)
                                         throws PersistenceException

Build the URL to be used for a remote connection, based on the given URL and database.

Parameters:

url - The URL as received from the remote server.

database - The database to which this URL belongs.

Returns:

The built URL as to be used for a remote connection.

Throws:

PersistenceException - if the specified connection URL is invalid.

createSequenceHandler

public abstract SequenceHandler createSequenceHandler(java.lang.String ldbName)

Creates and returns a SequenceHandler for a database.

Parameters:

ldbName - The logical name of the database to create the SequenceHandler for.

Returns:

A SequenceHandler for respective database.

injectComputedColumns

public abstract boolean injectComputedColumns()

Report whether the computed columns should be injected on table creating.

Returns:

true if the computed columns should be injected on table creating else false.

isUniqueConstraintViolation

public abstract boolean isUniqueConstraintViolation(java.sql.SQLException sqle)

Checks if the SQLState of the SQLException matches the dialect specific UNIQUE_VIOLATION code.

Parameters:

sqle - The SQLException that is causing the unique constraint violation.

Returns:

true if the SQLState matches the dialect specific code for UNIQUE_VIOLATION, false otherwise.

getComputedColumnString

public java.lang.String getComputedColumnString(java.lang.String name,
                                                java.lang.String type,
                                                int scale,
                                                boolean cs)

Constructs and returns the declaration of a computed column based on its name, type, scale, and case-sensitiveness.

Parameters:

name - The original column name.

type - The original column type.

scale - The optional scale, if needed.

cs - The case-sensitiveness.

Returns:

The declaration of the computed column(s) or null if not needed.

quote

public java.lang.String quote(java.lang.String expr)

Apply dialect-specific quoting.

Parameters:

expr - String expression.

Returns:

The quoted value.

getIndexLengthLimit

public int getIndexLengthLimit()

Some dialects have constraints about the maximum size of fields that compose an index. This method reports the dialect-specific index length limit, if any.

Returns:

Dialect-specific index length limit. If there are no such limits for this dialog, the method returns 0.

computeIndexKeySize

public int computeIndexKeySize(java.lang.Class<? extends BaseDataType> type,
                               java.lang.Object val)

Computes the size (in bytes) occupied by this value when stored as index-key in an index. It only make sense to call this method if the getIndexLengthLimit() returns positive values. If this dialect does not have index-size constraints then this method does not need to be overridden.

Parameters:

type - The type to be analyzed.

val - The actual value. Except for the char datatype, only the type of value is used, the actual value is not needed to determine the size occupied by the value as index-key.

Returns:

the size (in bytes) occupied by this value when stored as index-key in an index.

getSyntheticIndexSize

public abstract int getSyntheticIndexSize(boolean unique)

Returns the size of the synthetic part of the index. At this moment only the id of the record may be additionally added to an index to add custom properties (eg uniqueness) but other fields could be added. This part of the index is not visible using index reflection routines from IndexHelper. The synthetic components may differ between unique and non-unique indexes.

Parameters:

unique - true if the index is unique

Returns:

The size of synthetic part of the index, in bytes.

addRtrimmedExpression

public abstract void addRtrimmedExpression(java.lang.String expr,
                                           java.lang.StringBuilder sb)

Composes a rtrim equivalent call for a specified expression. This is dialect specific. Usually the returned value looks like:

    rtrim(expr)
 

The rtrim-med expression is appended to the string builder. The return value (the number of occurrences of the initial expr added to sb) should be use by caller to count the number of possible parameters from a query.

Parameters:

expr - The expression to be rtrim -med. It's up to the caller if it is a qualified field or not or any other kind of character-type expression.

sb - The StringBuilder to append the trimmed field to.

getMaxParameterCount

public int getMaxParameterCount()

Obtain the number of parameters a query of this dialect is allowed by the SQL server. If the query need more parameter it have to be rewritten or split and the result reassembled in memory.

Returns:

the maximum number of parameters that a query may have or 0 if there is no such limitation.

getCreateTableString

public java.lang.String getCreateTableString()

Returns the beginning of the DDL statement for creating a permanent table.

Returns:

the beginning of the DDL statement for creating a permanent table.

getCreateTemporaryTableString

public abstract java.lang.String getCreateTemporaryTableString(boolean ifNotExist)

Return the beginning of the DDL statement that creates a temporary table.

Parameters:

ifNotExist - If true a dialect-specific, optional if not exist clause is added.

Returns:

A string representing the beginning of the DDL statement that creates a temporary table.

getCreateTemporaryTablePostfix

public abstract java.lang.String getCreateTemporaryTablePostfix(boolean noUndo)

Return the ending of the DDL statement that creates a temporary table.

Parameters:

noUndo - If true, this function will return the keyword specific to no-undo temp-tables.

Returns:

A string representing the ending of the DDL statement that creates a temporary table, if any, or empty string otherwise.

getCreateIndexString

public java.lang.String getCreateIndexString(boolean unique)

Returns the beginning of the DDL statement for creating an index.

Parameters:

unique - true for unique indexes.

Returns:

the beginning of the DDL statement for creating an index.

getCreateIndexString

public java.lang.String getCreateIndexString(boolean unique,
                                             boolean softUnique)

Returns the beginning of the DDL statement for creating an index.

Parameters:

unique - true for unique indexes.

softUnique - true for soft-unique indexes.

Returns:

the beginning of the DDL statement for creating an index.

getDropIndexString

public abstract java.lang.String getDropIndexString(boolean ifExists,
                                                    java.lang.String idxName,
                                                    java.lang.String tableName)

Obtain a DDL statement which drops a SQL index.

Parameters:

ifExists - Flag that requires that the DDL include an optional IF EXIST clause.

idxName - The name of the index to be dropped by this DDL.

tableName - The name of the table to which the index belongs to. (Optional, is needed by the dialect).

Returns:

a DDL statement which drops a SQL index.

getDropTableString

public abstract java.lang.String getDropTableString(boolean ifExists,
                                                    java.lang.String tableName)

Obtain a DDL statement which drops a SQL table.

Parameters:

ifExists - Flag that requires that the DDL include an optional IF EXIST clause.

tableName - The name of the table to be dropped by this DDL.

Returns:

a DDL statement which drops a SQL index.

getSpecificTypeAsString

public java.lang.String getSpecificTypeAsString(FqlType type)

Converts and return the specified FqlType to a string representation which can be used in a SQL query (cast or other construct).

Parameters:

type - The type to be converted to string.

Returns:

A dialect specific string representation of the respective fql data type.

getSqlMappedType

public java.lang.String getSqlMappedType(java.lang.Class<?> fwdType,
                                         int scale,
                                         java.lang.Boolean caseSensitive)

Get the SQL mapping for a specific FWD data type.

Parameters:

fwdType - The FWD type.

scale - Optional scale parameter (for decimal data type).

Returns:

The string representation of the SQL datatype mapped by fwdType.

getSqlMappedType

public java.lang.String getSqlMappedType(java.lang.String fwdType,
                                         int scale,
                                         java.lang.Boolean caseSensitive)

Get the SQL mapping for a specific FWD data type.

Parameters:

fwdType - The class name of the FWD datatype.

scale - Optional scale parameter (for decimal data type).

Returns:

The string representation of the SQL datatype mapped by fwdType.

getAnalyzeString

public abstract java.lang.String getAnalyzeString(java.lang.String table)

Construct and return a string which represents the analyze or similar statements for this dialect. If the table is not null the statement will analyze only the respective table. Otherwise, all the tables are analyzed.

Parameters:

table - The name of the table to be analyzed. If null, all tables from the database will be analyzed, if possible.

Returns:

The analyze statement as requested. If the dialect does not support the analyze statement in the form requested null is returned.

orderByNulls

public int orderByNulls(java.lang.StringBuilder sb,
                        java.lang.String expression,
                        java.lang.String field,
                        boolean asc,
                        boolean forceAsc)

Determine if the sort component or index needs to be augmented with a NULLS FIRST/LAST option and add the required expression(s) as needed by this dialect. The default implementation does not augment the expression in any way.

Parameters:

sb - The StringBuilder which contains the SQL statement to be built.

expression - The field name (or expression) which is the current criterion to be augmented.

field - The field name which is the base of the previous parameter (possible null, ignored here).

asc - The sort direction.

forceAsc - If true, force the insertion of the default asc direction.

Returns:

the number of expressions which were added to the string builder.

weightAggregator

public java.util.Optional<Dialect.WeightAggregator> weightAggregator()

Get the WeightAggregator instance for the dialect if defined

Returns:

the WeightAggregator instance for the dialect if defined

translateToParmType

public ParmType translateToParmType(java.lang.String type,
                                    java.lang.String comment)

Translation from database column type to ParmType. This is a general implementation that will work for common types used in FWD. For fine-tuning, you can override it in specific dialects. TODO: should be abstract

Parameters:

type - column type

comment - comment with optional specification of type

Returns:

ParmType

getDecimals

public java.lang.Long getDecimals(java.lang.String type,
                                  java.lang.String decimals,
                                  java.lang.String comment)

Get decimals value for types that support it. This is a general implementation that will work for common types used in FWD. For fine-tuning, you can override it in specific dialects.

Parameters:

type - column type

decimals - decimals value as provided by the database

comment - comment with optional metadata

Returns:

decimals value or null (for types that don't support decimals)

getAddForeignKeyConstraintString

public java.lang.String getAddForeignKeyConstraintString(java.lang.String table,
                                                         java.lang.String fkName,
                                                         java.lang.String fkFields,
                                                         java.lang.String refTable,
                                                         java.lang.String refFields,
                                                         java.lang.String indent,
                                                         java.lang.String eoln)

Creates and returns a string which represent the alter table statement for adding a new foreign key constraint.

Parameters:

table - The table to be altered.

fkName - The name of the constraint.

fkFields - Comma separated names of the fields which make the reference to parent table.

refTable - The parent / referred table.

refFields - Comma separated names of the fields which uniquely identify the record in parent table.

indent - The indentation for pretty print the result.

eoln - OS-specific end of line terminator (if the result is a multiline).

Returns:

A string used to create the foreign key constraint as described above.

getCatalogPattern

public java.lang.String getCatalogPattern(Database database)

Provides catalog matching pattern to load data correctly from JDBC.

Parameters:

database - database object

Returns:

catalog pattern

getSchemaPattern

public java.lang.String getSchemaPattern(Database database)

Provides schema matching pattern to load data correctly from JDBC.

Parameters:

database - database object

Returns:

schema pattern

supportsLazyQueryResultsMode

public boolean supportsLazyQueryResultsMode()

Determine if the Dialect supports queries executed in a lazy manner. Unless implemented, lazy queries are not supported.

Returns:

false By default, lazy queries are not supported.

allowDBUniqueCheck

public boolean allowDBUniqueCheck()

Determine if the Dialect supports index validation (with the VALIDATE keyword).

Returns:

false By default, VALIDATE is not supported.

getSequenceSQL

public java.lang.String getSequenceSQL(Database database)

Provides SQL to load sequences.

Parameters:

database - database object

Returns:

sequence SQL

checkIndexConstraints

public void checkIndexConstraints(P2JIndex p2JIndex,
                                  java.util.Map<java.lang.String,P2JField> fields)

If the dialect has some constraints about the index size, do the calculations and report any possible error/warning when the database schema is set.

The default implementation does nothing.

Parameters:

p2JIndex - The index to be processed.

fields - All table fields, mapped by their legacy name.

preparePermanentDatabase

public void preparePermanentDatabase(Database db)
                              throws PersistenceException

Prepare the specified database by creating all necessary function aliases and setting global parameters.

The default implementation from Dialect does nothing.

Parameters:

db - Database to prepare.

Throws:

PersistenceException - if there is any error executing DDL.

getSqlIndexName

public java.lang.String getSqlIndexName(P2JIndex index)

Obtain the name of an index. The implementing dialect may override this method in order to make sure the name is unique among tables.

Parameters:

index - The index structure.

Returns:

the SQL name of the index.

allowSelectWildcard

public boolean allowSelectWildcard()

Check if this dialect allows the selection of fields using * wildcard. Also, quantification should also be supported if this is allowed (alias.*).

Returns:

true if we can use * as selection wildcard.

getMaxEntriesInSelect

public int getMaxEntriesInSelect()

Returns the max numbers of fields selected that the dialect can allow without throwing an error.

Returns:

Maximum of selected fields allowed

getCodepage

public java.lang.String getCodepage(java.sql.Connection conn)

Use the provided database connection to extract the codepage/CharSet used by the database and report it back to the caller.

Parameters:

conn - The JDBC database connection to be used.

Returns:

The name of the codepage/CharSet used by the database to store character data.

getCollation

public java.lang.String getCollation(java.sql.Connection conn)

Use the provided database connection to extract the collation used by the database and report it back to the caller.

Parameters:

conn - The JDBC database connection to be used.

Returns:

The name of the collation used by the database to store character data.