DB2Dialect (JBoss Application Server: Build 7.1.2.Final API)

java.lang.Object
- org.hibernate.dialect.Dialect
- - org.hibernate.dialect.DB2Dialect

All Implemented Interfaces:

ConversionContext

Direct Known Subclasses:

DB2390Dialect, DB2400Dialect, DerbyDialect
```
public class DB2Dialect
extends Dialect
```
An SQL dialect for DB2.

Author:

Gavin King

Field Summary
- Fields inherited from class org.hibernate.dialect.Dialect
  CLOSED_QUOTE, DEFAULT_BATCH_SIZE, LEGACY_LOB_MERGE_STRATEGY, NEW_LOCATOR_LOB_MERGE_STRATEGY, NO_BATCH, QUOTE, STREAM_XFER_LOB_MERGE_STRATEGY

Constructor Summary

Constructors
Constructor and Description

DB2Dialect()

Constructors
Constructor and Description
`DB2Dialect()`

Method Summary

Methods
Modifier and Type	Method and Description
`int`	`convertToFirstRowValue(int zeroBasedFirstResult)` DB2 does have a one-based offset, however this was actually already handled in the limit string building (the '?+1' bit).
`boolean`	`doesReadCommittedCauseWritersToBlockReaders()` For the underlying database, is READ_COMMITTED isolation implemented by forcing readers to wait for write locks to be released?
`boolean`	`dropConstraints()` Do we need to drop constraints before dropping tables in this dialect?
`String`	`generateTemporaryTableName(String baseTableName)` Generate a temporary table name given the base table.
`String`	`getAddColumnString()` The syntax used to add a column to a table (optional).
`String`	`getCreateSequenceString(String sequenceName)` Typically dialects which support sequences can create a sequence with a single command.
`String`	`getCreateTemporaryTablePostfix()` Get any fragments needing to be postfixed to the command for temporary table creation.
`String`	`getCreateTemporaryTableString()` Command used to create a temporary table.
`String`	`getCrossJoinSeparator()`
`String`	`getCurrentTimestampSelectString()` Retrieve the command used to retrieve the current timestamp from the database.
`String`	`getDropSequenceString(String sequenceName)` Typically dialects which support sequences can drop a sequence with a single command.
`String`	`getForUpdateString()` Get the string to append to SELECT statements to acquire locks for this dialect.
`String`	`getIdentityColumnString()` The syntax used during DDL to define a column as being an IDENTITY.
`String`	`getIdentityInsertString()` The keyword used to insert a generated value into an identity column (or null).
`String`	`getIdentitySelectString()` Get the select command to use to retrieve the last generated IDENTITY value.
`String`	`getLimitString(String sql, int offset, int limit)` Given a limit and an offset, apply the limit clause to the query.
`String`	`getLowercaseFunction()` The name of the SQL function that transforms a string to lowercase
`String`	`getQuerySequencesString()` Get the select command used retrieve the names of all sequences.
`ResultSet`	`getResultSet(CallableStatement ps)` Given a callable statement previously processed by `Dialect.registerResultSetOutParameter(java.sql.CallableStatement, int)`, extract the `ResultSet` from the OUT parameter.
`String`	`getSelectClauseNullString(int sqlType)` Given a `Types` type code, determine an appropriate null value to use in a select clause.
`String`	`getSequenceNextValString(String sequenceName)` Generate the appropriate select statement to to retrieve the next value of a sequence.
`boolean`	`isCurrentTimestampSelectStringCallable()` Should the value returned by `Dialect.getCurrentTimestampSelectString()` be treated as callable.
`static void`	`main(String[] args)`
`int`	`registerResultSetOutParameter(CallableStatement statement, int col)` Registers an OUT parameter which will be returning a `ResultSet`.
`boolean`	`requiresCastingOfParametersInSelectClause()` DB2 in fact does require that parameters appearing in the select clause be wrapped in cast() calls to tell the DB parser the type of the select value.
`boolean`	`supportsCommentOn()`
`boolean`	`supportsCurrentTimestampSelection()` Does this dialect support a way to retrieve the database's current timestamp value?
`boolean`	`supportsEmptyInList()` Does this dialect support empty IN lists? For example, is [where XYZ in ()] a supported construct?
`boolean`	`supportsExistsInSelect()` Does the dialect support an exists statement in the select clause?
`boolean`	`supportsIdentityColumns()` Does this dialect support identity column key generation?
`boolean`	`supportsLimit()` Does this dialect support some form of limiting query results via a SQL clause?
`boolean`	`supportsLobValueChangePropogation()` Does the dialect support propagating changes to LOB values back to the database? Talking about mutating the internal value of the locator as opposed to supplying a new locator instance...
`boolean`	`supportsNotNullUnique()`
`boolean`	`supportsOuterJoinForUpdate()` Does this dialect support `FOR UPDATE` in conjunction with outer joined rows?
`boolean`	`supportsParametersInInsertSelect()` Does this dialect support parameters within the `SELECT` clause of `INSERT ...`
`boolean`	`supportsPooledSequences()` Does this dialect support "pooled" sequences.
`boolean`	`supportsResultSetPositionQueryMethodsOnForwardOnlyCursor()` Does this dialect support asking the result set its positioning information on forward only cursors.
`boolean`	`supportsSequences()` Does this dialect support sequences?
`boolean`	`supportsTemporaryTables()` Does this dialect support temporary tables?
`boolean`	`supportsTupleDistinctCounts()` Does this dialect support `count(distinct a,b)`?
`boolean`	`supportsUnionAll()` Does this dialect support UNION ALL, which is generally a faster variant of UNION?
`boolean`	`supportsVariableLimit()` Does this dialect support bind variables (i.e., prepared statement parameters) for its limit/offset?
`boolean`	`useMaxForLimit()` Does the `LIMIT` clause take a "maximum" row number instead of a total number of returned rows? This is easiest understood via an example.

Methods inherited from class org.hibernate.dialect.Dialect
appendIdentitySelectToInsert, appendLockHint, applyLocksToSql, areStringComparisonsCaseInsensitive, bindLimitParametersFirst, bindLimitParametersInReverseOrder, buildSQLExceptionConversionDelegate, buildSQLExceptionConverter, closeQuote, createCaseFragment, createOuterJoinFragment, doesRepeatableReadCauseReadersToBlockWriters, dropTemporaryTableAfterUse, forceLimitUsage, forUpdateOfColumns, getAddForeignKeyConstraintString, getAddPrimaryKeyConstraintString, getAddUniqueConstraintString, getCascadeConstraintsString, getCaseInsensitiveLike, getCastTypeName, getColumnAliasExtractor, getColumnComment, getCreateMultisetTableString, getCreateSequenceString, getCreateSequenceStrings, getCreateSequenceStrings, getCreateTableString, getCurrentTimestampSQLFunctionName, getDefaultProperties, getDialect, getDialect, getDropForeignKeyString, getDropSequenceStrings, getDropTemporaryTableString, getForUpdateNowaitString, getForUpdateNowaitString, getForUpdateString, getForUpdateString, getForUpdateString, getForUpdateString, getFunctions, getHibernateTypeName, getHibernateTypeName, getIdentityColumnString, getIdentitySelectString, getKeywords, getLimitString, getLobMergeStrategy, getLockingStrategy, getMaxAliasLength, getNativeIdentifierGeneratorClass, getNoColumnsInsertString, getNullColumnString, getReadLockString, getSelectGUIDString, getSelectSequenceNextValString, getSqlTypeDescriptorOverride, getTableComment, getTableTypeString, getTypeName, getTypeName, getViolatedConstraintNameExtracter, getWriteLockString, hasAlterTable, hasDataTypeInIdentityColumn, hasSelfReferentialForeignKeyBug, isLockTimeoutParameterized, openQuote, performTemporaryTableDDLInIsolation, qualifyIndexName, quote, registerColumnType, registerColumnType, registerFunction, registerHibernateType, registerHibernateType, registerKeyword, remapSqlTypeDescriptor, replaceResultVariableInOrderByClauseWithPosition, supportsBindAsCallableArgument, supportsCascadeDelete, supportsCaseInsensitiveLike, supportsCircularCascadeDeleteConstraints, supportsColumnCheck, supportsExpectedLobUsagePattern, supportsIfExistsAfterTableName, supportsIfExistsBeforeTableName, supportsInsertSelectIdentity, supportsLimitOffset, supportsLockTimeouts, supportsRowValueConstructorSyntax, supportsRowValueConstructorSyntaxInInList, supportsSubqueryOnMutatingTable, supportsSubselectAsInPredicateLHS, supportsTableCheck, supportsTupleCounts, supportsUnboundedLobLocatorMaterialization, supportsUnique, supportsUniqueConstraintInCreateAlterTable, toBooleanValueString, toString, transformSelectString, useInputStreamToInsertBlob

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - DB2Dialect
```
public DB2Dialect()
```
- Method Detail
  - getLowercaseFunction
```
public String getLowercaseFunction()
```
    Description copied from class: Dialect
    
    The name of the SQL function that transforms a string to lowercase
    
    Overrides:
    
    getLowercaseFunction in class Dialect
    
    Returns:
    The dialect-specific lowercase function.
  - getAddColumnString
```
public String getAddColumnString()
```
    Description copied from class: Dialect
    
    The syntax used to add a column to a table (optional).
    
    Overrides:
    
    getAddColumnString in class Dialect
    
    Returns:
    The "add column" fragment.
  - dropConstraints
```
public boolean dropConstraints()
```
    Description copied from class: Dialect
    
    Do we need to drop constraints before dropping tables in this dialect?
    
    Overrides:
    
    dropConstraints in class Dialect
    
    Returns:
    True if constraints must be dropped prior to dropping the table; false otherwise.
  - supportsIdentityColumns
```
public boolean supportsIdentityColumns()
```
    Description copied from class: Dialect
    
    Does this dialect support identity column key generation?
    
    Overrides:
    
    supportsIdentityColumns in class Dialect
    
    Returns:
    True if IDENTITY columns are supported; false otherwise.
  - getIdentitySelectString
```
public String getIdentitySelectString()
```
    Description copied from class: Dialect
    
    Get the select command to use to retrieve the last generated IDENTITY value.
    
    Overrides:
    
    getIdentitySelectString in class Dialect
    
    Returns:
    The appropriate select command
  - getIdentityColumnString
```
public String getIdentityColumnString()
```
    Description copied from class: Dialect
    
    The syntax used during DDL to define a column as being an IDENTITY.
    
    Overrides:
    
    getIdentityColumnString in class Dialect
    
    Returns:
    The appropriate DDL fragment.
  - getIdentityInsertString
```
public String getIdentityInsertString()
```
    Description copied from class: Dialect
    
    The keyword used to insert a generated value into an identity column (or null). Need if the dialect does not support inserts that specify no column values.
    
    Overrides:
    
    getIdentityInsertString in class Dialect
    
    Returns:
    The appropriate keyword.
  - getSequenceNextValString
```
public String getSequenceNextValString(String sequenceName)
```
    Description copied from class: Dialect
    
    Generate the appropriate select statement to to retrieve the next value of a sequence.
    This should be a "stand alone" select statement.
    
    Overrides:
    
    getSequenceNextValString in class Dialect
    
    Parameters:
    sequenceName - the name of the sequence
    
    Returns:
    String The "nextval" select string.
  - getCreateSequenceString
```
public String getCreateSequenceString(String sequenceName)
```
    Description copied from class: Dialect
    
    Typically dialects which support sequences can create a sequence with a single command. This is convenience form of Dialect.getCreateSequenceStrings(java.lang.String) to help facilitate that.
    Dialects which support sequences and can create a sequence in a single command need *only* override this method. Dialects which support sequences but require multiple commands to create a sequence should instead override Dialect.getCreateSequenceStrings(java.lang.String).
    
    Overrides:
    
    getCreateSequenceString in class Dialect
    
    Parameters:
    sequenceName - The name of the sequence
    
    Returns:
    The sequence creation command
  - getDropSequenceString
```
public String getDropSequenceString(String sequenceName)
```
    Description copied from class: Dialect
    
    Typically dialects which support sequences can drop a sequence with a single command. This is convenience form of Dialect.getDropSequenceStrings(java.lang.String) to help facilitate that.
    Dialects which support sequences and can drop a sequence in a single command need *only* override this method. Dialects which support sequences but require multiple commands to drop a sequence should instead override Dialect.getDropSequenceStrings(java.lang.String).
    
    Overrides:
    
    getDropSequenceString in class Dialect
    
    Parameters:
    sequenceName - The name of the sequence
    
    Returns:
    The sequence drop commands
  - supportsSequences
```
public boolean supportsSequences()
```
    Description copied from class: Dialect
    
    Does this dialect support sequences?
    
    Overrides:
    
    supportsSequences in class Dialect
    
    Returns:
    True if sequences supported; false otherwise.
  - supportsPooledSequences
```
public boolean supportsPooledSequences()
```
    Description copied from class: Dialect
    
    Does this dialect support "pooled" sequences. Not aware of a better name for this. Essentially can we specify the initial and increment values?
    
    Overrides:
    
    supportsPooledSequences in class Dialect
    
    Returns:
    True if such "pooled" sequences are supported; false otherwise.
    See Also:
    Dialect.getCreateSequenceStrings(String, int, int), Dialect.getCreateSequenceString(String, int, int)
  - getQuerySequencesString
```
public String getQuerySequencesString()
```
    Description copied from class: Dialect
    
    Get the select command used retrieve the names of all sequences.
    
    Overrides:
    
    getQuerySequencesString in class Dialect
    
    Returns:
    The select command; or null if sequences are not supported.
    See Also:
    SchemaUpdate
  - supportsLimit
```
public boolean supportsLimit()
```
    Description copied from class: Dialect
    
    Does this dialect support some form of limiting query results via a SQL clause?
    
    Overrides:
    
    supportsLimit in class Dialect
    
    Returns:
    True if this dialect supports some form of LIMIT.
  - supportsVariableLimit
```
public boolean supportsVariableLimit()
```
    Description copied from class: Dialect
    
    Does this dialect support bind variables (i.e., prepared statement parameters) for its limit/offset?
    
    Overrides:
    
    supportsVariableLimit in class Dialect
    
    Returns:
    True if bind variables can be used; false otherwise.
  - getLimitString
```
public String getLimitString(String sql,
                    int offset,
                    int limit)
```
    Description copied from class: Dialect
    
    Given a limit and an offset, apply the limit clause to the query.
    
    Overrides:
    
    getLimitString in class Dialect
    
    Parameters:
    sql - The query to which to apply the limit.
    offset - The offset of the limit
    limit - The limit of the limit ;)
    
    Returns:
    The modified query statement with the limit applied.
  - convertToFirstRowValue
```
public int convertToFirstRowValue(int zeroBasedFirstResult)
```
    DB2 does have a one-based offset, however this was actually already handled in the limit string building (the '?+1' bit). To not mess up inheritors, I'll leave that part alone and not touch the offset here.
    
    Overrides:
    
    convertToFirstRowValue in class Dialect
    
    Parameters:
    zeroBasedFirstResult - The user-supplied, zero-based offset
    
    Returns:
    zeroBasedFirstResult
    See Also:
    Query.setFirstResult(int), Criteria.setFirstResult(int)
  - getForUpdateString
```
public String getForUpdateString()
```
    Description copied from class: Dialect
    
    Get the string to append to SELECT statements to acquire locks for this dialect.
    
    Overrides:
    
    getForUpdateString in class Dialect
    
    Returns:
    The appropriate FOR UPDATE clause string.
  - useMaxForLimit
```
public boolean useMaxForLimit()
```
    Description copied from class: Dialect
    
    Does the LIMIT clause take a "maximum" row number instead of a total number of returned rows?
    This is easiest understood via an example. Consider you have a table with 20 rows, but you only want to retrieve rows number 11 through 20. Generally, a limit with offset would say that the offset = 11 and the limit = 10 (we only want 10 rows at a time); this is specifying the total number of returned rows. Some dialects require that we instead specify offset = 11 and limit = 20, where 20 is the "last" row we want relative to offset (i.e. total number of rows = 20 - 11 = 9)
    So essentially, is limit relative from offset? Or is limit absolute?
    
    Overrides:
    
    useMaxForLimit in class Dialect
    
    Returns:
    True if limit is relative from offset; false otherwise.
  - supportsOuterJoinForUpdate
```
public boolean supportsOuterJoinForUpdate()
```
    Description copied from class: Dialect
    
    Does this dialect support FOR UPDATE in conjunction with outer joined rows?
    
    Overrides:
    
    supportsOuterJoinForUpdate in class Dialect
    
    Returns:
    True if outer joined rows can be locked via FOR UPDATE.
  - supportsNotNullUnique
```
public boolean supportsNotNullUnique()
```
    Overrides:
    
    supportsNotNullUnique in class Dialect
  - supportsExistsInSelect
```
public boolean supportsExistsInSelect()
```
    Description copied from class: Dialect
    
    Does the dialect support an exists statement in the select clause?
    
    Overrides:
    
    supportsExistsInSelect in class Dialect
    
    Returns:
    True if exists checks are allowed in the select clause; false otherwise.
  - getSelectClauseNullString
```
public String getSelectClauseNullString(int sqlType)
```
    Description copied from class: Dialect
    
    Given a Types type code, determine an appropriate null value to use in a select clause.
    One thing to consider here is that certain databases might require proper casting for the nulls here since the select here will be part of a UNION/UNION ALL.
    
    Overrides:
    
    getSelectClauseNullString in class Dialect
    
    Parameters:
    sqlType - The Types type code.
    
    Returns:
    The appropriate select clause value fragment.
  - main
```
public static void main(String[] args)
```
  - supportsUnionAll
```
public boolean supportsUnionAll()
```
    Description copied from class: Dialect
    
    Does this dialect support UNION ALL, which is generally a faster variant of UNION?
    
    Overrides:
    
    supportsUnionAll in class Dialect
    
    Returns:
    True if UNION ALL is supported; false otherwise.
  - registerResultSetOutParameter
```
public int registerResultSetOutParameter(CallableStatement statement,
                                int col)
                                  throws SQLException
```
    Description copied from class: Dialect
    
    Registers an OUT parameter which will be returning a ResultSet. How this is accomplished varies greatly from DB to DB, hence its inclusion (along with Dialect.getResultSet(java.sql.CallableStatement)) here.
    
    Overrides:
    
    registerResultSetOutParameter in class Dialect
    
    Parameters:
    statement - The callable statement.
    col - The bind position at which to register the OUT param.
    
    Returns:
    The number of (contiguous) bind positions used.
    
    Throws:
    
    SQLException - Indicates problems registering the OUT param.
  - getResultSet
```
public ResultSet getResultSet(CallableStatement ps)
                       throws SQLException
```
    Description copied from class: Dialect
    
    Given a callable statement previously processed by Dialect.registerResultSetOutParameter(java.sql.CallableStatement, int), extract the ResultSet from the OUT parameter.
    
    Overrides:
    
    getResultSet in class Dialect
    
    Parameters:
    ps - The callable statement.
    
    Returns:
    The extracted result set.
    
    Throws:
    
    SQLException - Indicates problems extracting the result set.
  - supportsCommentOn
```
public boolean supportsCommentOn()
```
    Overrides:
    
    supportsCommentOn in class Dialect
  - supportsTemporaryTables
```
public boolean supportsTemporaryTables()
```
    Description copied from class: Dialect
    
    Does this dialect support temporary tables?
    
    Overrides:
    
    supportsTemporaryTables in class Dialect
    
    Returns:
    True if temp tables are supported; false otherwise.
  - getCreateTemporaryTableString
```
public String getCreateTemporaryTableString()
```
    Description copied from class: Dialect
    
    Command used to create a temporary table.
    
    Overrides:
    
    getCreateTemporaryTableString in class Dialect
    
    Returns:
    The command used to create a temporary table.
  - getCreateTemporaryTablePostfix
```
public String getCreateTemporaryTablePostfix()
```
    Description copied from class: Dialect
    
    Get any fragments needing to be postfixed to the command for temporary table creation.
    
    Overrides:
    
    getCreateTemporaryTablePostfix in class Dialect
    
    Returns:
    Any required postfix.
  - generateTemporaryTableName
```
public String generateTemporaryTableName(String baseTableName)
```
    Description copied from class: Dialect
    
    Generate a temporary table name given the base table.
    
    Overrides:
    
    generateTemporaryTableName in class Dialect
    
    Parameters:
    baseTableName - The table name from which to base the temp table name.
    
    Returns:
    The generated temp table name.
  - supportsCurrentTimestampSelection
```
public boolean supportsCurrentTimestampSelection()
```
    Description copied from class: Dialect
    
    Does this dialect support a way to retrieve the database's current timestamp value?
    
    Overrides:
    
    supportsCurrentTimestampSelection in class Dialect
    
    Returns:
    True if the current timestamp can be retrieved; false otherwise.
  - getCurrentTimestampSelectString
```
public String getCurrentTimestampSelectString()
```
    Description copied from class: Dialect
    
    Retrieve the command used to retrieve the current timestamp from the database.
    
    Overrides:
    
    getCurrentTimestampSelectString in class Dialect
    
    Returns:
    The command.
  - isCurrentTimestampSelectStringCallable
```
public boolean isCurrentTimestampSelectStringCallable()
```
    Description copied from class: Dialect
    
    Should the value returned by Dialect.getCurrentTimestampSelectString() be treated as callable. Typically this indicates that JDBC escape syntax is being used...
    
    Overrides:
    
    isCurrentTimestampSelectStringCallable in class Dialect
    
    Returns:
    True if the Dialect.getCurrentTimestampSelectString() return is callable; false otherwise.
  - supportsParametersInInsertSelect
```
public boolean supportsParametersInInsertSelect()
```
    Does this dialect support parameters within the SELECT clause of INSERT ... SELECT ... statements?
    DB2 is know to support parameters in the SELECT clause, but only in casted form (see requiresCastingOfParametersInSelectClause()).
    
    Overrides:
    
    supportsParametersInInsertSelect in class Dialect
    
    Returns:
    True.
  - requiresCastingOfParametersInSelectClause
```
public boolean requiresCastingOfParametersInSelectClause()
```
    DB2 in fact does require that parameters appearing in the select clause be wrapped in cast() calls to tell the DB parser the type of the select value.
    
    Overrides:
    
    requiresCastingOfParametersInSelectClause in class Dialect
    
    Returns:
    True.
  - supportsResultSetPositionQueryMethodsOnForwardOnlyCursor
```
public boolean supportsResultSetPositionQueryMethodsOnForwardOnlyCursor()
```
    Description copied from class: Dialect
    
    Does this dialect support asking the result set its positioning information on forward only cursors. Specifically, in the case of scrolling fetches, Hibernate needs to use ResultSet.isAfterLast() and ResultSet.isBeforeFirst(). Certain drivers do not allow access to these methods for forward only cursors.
    NOTE : this is highly driver dependent!
    
    Overrides:
    
    supportsResultSetPositionQueryMethodsOnForwardOnlyCursor in class Dialect
    
    Returns:
    True if methods like ResultSet.isAfterLast() and ResultSet.isBeforeFirst() are supported for forward only cursors; false otherwise.
  - getCrossJoinSeparator
```
public String getCrossJoinSeparator()
```
    Overrides:
    
    getCrossJoinSeparator in class Dialect
    
    Returns:
    Returns the separator to use for defining cross joins when translating HQL queries.
    Typically this will be either [ cross join ] or [, ]
    Note that the spaces are important!
  - supportsEmptyInList
```
public boolean supportsEmptyInList()
```
    Description copied from class: Dialect
    
    Does this dialect support empty IN lists?
    For example, is [where XYZ in ()] a supported construct?
    
    Overrides:
    
    supportsEmptyInList in class Dialect
    
    Returns:
    True if empty in lists are supported; false otherwise.
  - supportsLobValueChangePropogation
```
public boolean supportsLobValueChangePropogation()
```
    Description copied from class: Dialect
    
    Does the dialect support propagating changes to LOB values back to the database? Talking about mutating the internal value of the locator as opposed to supplying a new locator instance...
    For BLOBs, the internal value might be changed by: Blob.setBinaryStream(long), Blob.setBytes(long, byte[]), Blob.setBytes(long, byte[], int, int), or Blob.truncate(long).
    For CLOBs, the internal value might be changed by: Clob.setAsciiStream(long), Clob.setCharacterStream(long), Clob.setString(long, String), Clob.setString(long, String, int, int), or Clob.truncate(long).
    NOTE : I do not know the correct answer currently for databases which (1) are not part of the cruise control process or (2) do not Dialect.supportsExpectedLobUsagePattern().
    
    Overrides:
    
    supportsLobValueChangePropogation in class Dialect
    
    Returns:
    True if the changes are propagated back to the database; false otherwise.
  - doesReadCommittedCauseWritersToBlockReaders
```
public boolean doesReadCommittedCauseWritersToBlockReaders()
```
    Description copied from class: Dialect
    
    For the underlying database, is READ_COMMITTED isolation implemented by forcing readers to wait for write locks to be released?
    
    Overrides:
    
    doesReadCommittedCauseWritersToBlockReaders in class Dialect
    
    Returns:
    True if writers block readers to achieve READ_COMMITTED; false otherwise.
  - supportsTupleDistinctCounts
```
public boolean supportsTupleDistinctCounts()
```
    Description copied from class: Dialect
    
    Does this dialect support `count(distinct a,b)`?
    
    Overrides:
    
    supportsTupleDistinctCounts in class Dialect
    
    Returns:
    True if the database supports counting distinct tuples; false otherwise.

Class DB2Dialect

Field Summary

Fields inherited from class org.hibernate.dialect.Dialect

Constructor Summary

Method Summary

Methods inherited from class org.hibernate.dialect.Dialect

Methods inherited from class java.lang.Object

Constructor Detail

DB2Dialect

Method Detail

getLowercaseFunction

getAddColumnString

dropConstraints

supportsIdentityColumns

getIdentitySelectString

getIdentityColumnString

getIdentityInsertString

getSequenceNextValString

getCreateSequenceString

getDropSequenceString

supportsSequences

supportsPooledSequences

getQuerySequencesString

supportsLimit

supportsVariableLimit

getLimitString

convertToFirstRowValue

getForUpdateString

useMaxForLimit

supportsOuterJoinForUpdate

supportsNotNullUnique

supportsExistsInSelect

getSelectClauseNullString

main

supportsUnionAll

registerResultSetOutParameter

getResultSet

supportsCommentOn

supportsTemporaryTables

getCreateTemporaryTableString

getCreateTemporaryTablePostfix

generateTemporaryTableName

supportsCurrentTimestampSelection

getCurrentTimestampSelectString

isCurrentTimestampSelectStringCallable

supportsParametersInInsertSelect

requiresCastingOfParametersInSelectClause

supportsResultSetPositionQueryMethodsOnForwardOnlyCursor

getCrossJoinSeparator

supportsEmptyInList

supportsLobValueChangePropogation

doesReadCommittedCauseWritersToBlockReaders

supportsTupleDistinctCounts