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## org.hibernate.dialect
Class DB2Dialect

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

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, NO_BATCH, QUOTE`

Constructor Summary
`DB2Dialect()`

Method Summary
`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 bas 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` | `getCurrentTimestampSelectString()` Retrieve the command used to retrieve the current timestammp from the database.
`String` | `getCurrentTimestampSQLFunctionName()` The name of the database-specific SQL function for retrieving the current timestamp.
`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, boolean hasOffset)` Apply s 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 retreive 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 returing a `ResultSet`.
`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` | `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 propogating 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` | `supportsSequences()` Does this dialect support sequences?
`boolean` | `supportsTemporaryTables()` Does this dialect support temporary tables?
`boolean` | `supportsUnionAll()` Does this dialect support UNION ALL, which is generally a faster variant of UNION?
`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, buildSQLExceptionConverter, closeQuote, createCaseFragment, createOuterJoinFragment, doesReadCommittedCauseWritersToBlockReaders, doesRepeatableReadCauseReadersToBlockWriters, dropTemporaryTableAfterUse, forUpdateOfColumns, getAddForeignKeyConstraintString, getAddPrimaryKeyConstraintString, getCascadeConstraintsString, getCastTypeName, getColumnComment, getCreateMultisetTableString, getCreateSequenceString, getCreateSequenceStrings, getCreateSequenceStrings, getCreateTableString, getDefaultProperties, getDialect, getDialect, getDropForeignKeyString, getDropSequenceStrings, getForUpdateNowaitString, getForUpdateNowaitString, getForUpdateString, getForUpdateString, getFunctions, getHibernateTypeName, getHibernateTypeName, getIdentityColumnString, getIdentitySelectString, getKeywords, getLimitString, getLockingStrategy, getMaxAliasLength, getNativeIdentifierGeneratorClass, getNoColumnsInsertString, getNullColumnString, getSelectGUIDString, getSelectSequenceNextValString, getTableComment, getTableTypeString, getTypeName, getTypeName, getViolatedConstraintNameExtracter, hasAlterTable, hasDataTypeInIdentityColumn, hasSelfReferentialForeignKeyBug, openQuote, performTemporaryTableDDLInIsolation, qualifyIndexName, quote, registerColumnType, registerColumnType, registerFunction, registerHibernateType, registerHibernateType, registerKeyword, supportsBindAsCallableArgument, supportsCascadeDelete, supportsCircularCascadeDeleteConstraints, supportsColumnCheck, supportsExistsInSelect, supportsExpectedLobUsagePattern, supportsIfExistsAfterTableName, supportsIfExistsBeforeTableName, supportsInsertSelectIdentity, supportsLimitOffset, supportsPooledSequences, supportsResultSetPositionQueryMethodsOnForwardOnlyCursor, supportsRowValueConstructorSyntax, supportsRowValueConstructorSyntaxInInList, supportsSubqueryOnMutatingTable, supportsSubselectAsInPredicateLHS, supportsTableCheck, supportsUnboundedLobLocatorMaterialization, supportsUnique, supportsUniqueConstraintInCreateAlterTable, supportsVariableLimit, 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 retreive 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.

### 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.

### getLimitString

    public String getLimitString(String sql,
                                 boolean hasOffset)

  Description copied from class: `Dialect`
  Apply s limit clause to the query.

  Typically dialects utilize `variable` limit caluses when they support limits. Thus, when building the select command we do not actually need to know the limit or the offest since we will just be using placeholders.

  Here we do still pass along whether or not an offset was specified so that dialects not supporting offsets can generate proper exceptions. In general, dialects will override one or the other of this method and `Dialect.getLimitString(String, int, int)`.

  Overrides:
    `getLimitString` in class `Dialect`
  Parameters:
    `sql` - The query to which to apply the limit.
    `hasOffset` - Is the query requesting an offset?
  Returns:
    the modified SQL

### 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`

### 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 returing 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 bas 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 timestammp 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 sytnax is being used...

  Overrides:
    `isCurrentTimestampSelectStringCallable` in class `Dialect`
  Returns:
    True if the `Dialect.getCurrentTimestampSelectString()` return is callable; false otherwise.

### supportsParametersInInsertSelect

    public boolean supportsParametersInInsertSelect()

  Description copied from class: `Dialect`
  Does this dialect support parameters within the select clause of INSERT ... SELECT ... statements?

  Overrides:
    `supportsParametersInInsertSelect` in class `Dialect`
  Returns:
    True if this is supported; false otherwise.

### getCurrentTimestampSQLFunctionName

    public String getCurrentTimestampSQLFunctionName()

  Description copied from class: `Dialect`
  The name of the database-specific SQL function for retrieving the current timestamp.

  Overrides:
    `getCurrentTimestampSQLFunctionName` in class `Dialect`
  Returns:
    The function name.

### 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 propogating 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 propogated back to the database; false otherwise.

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