mondrian.spi.impl
Class MySqlDialect

java.lang.Object
  mondrian.spi.impl.JdbcDialectImpl
      mondrian.spi.impl.MySqlDialect

All Implemented Interfaces:

Dialect

Direct Known Subclasses:

InfobrightDialect

public class MySqlDialect
extends JdbcDialectImpl

Implementation of Dialect for the MySQL database.

Since:

Nov 23, 2008

Version:

$Id: //open/mondrian/src/main/mondrian/spi/impl/MySqlDialect.java#12 $

Author:

jhyde

Nested Class Summary

Nested classes/interfaces inherited from interface mondrian.spi.Dialect

Dialect.DatabaseProduct, Dialect.Datatype, Dialect.NullCollation

Field Summary

static JdbcDialectFactory

FACTORY

Fields inherited from class mondrian.spi.impl.JdbcDialectImpl

databaseProduct, permitsSelectNotInGroupBy, productVersion

Constructor Summary

MySqlDialect(java.sql.Connection connection)
Creates a MySqlDialect.

Method Summary

boolean	allowsCompoundCountDistinct() Returns whether this Dialect allows multiple arguments to the COUNT(DISTINCT ...) aggregate function, for example SELECT COUNT(DISTINCT x, y) FROM t
boolean	allowsFromQuery() Returns whether this Dialect allows a subquery in the from clause, for example SELECT * FROM (SELECT * FROM t) AS x
void	appendHintsAfterFromClause(java.lang.StringBuilder buf, java.util.Map<java.lang.String,java.lang.String> hints) Assembles and returns a string containing any hints that should be appended after the FROM clause in a SELECT statement, based on any hints provided.
protected java.lang.String	deduceIdentifierQuoteString(java.sql.DatabaseMetaData databaseMetaData)
protected java.lang.String	deduceProductName(java.sql.DatabaseMetaData databaseMetaData)
protected boolean	deduceSupportsSelectNotInGroupBy(java.sql.Connection connection) Detects whether the database is configured to permit queries that include columns in the SELECT that are not also in the GROUP BY.
java.lang.String	generateInline(java.util.List<java.lang.String> columnNames, java.util.List<java.lang.String> columnTypes, java.util.List<java.lang.String[]> valueList) Generates a SQL statement to represent an inline dataset.
java.lang.String	generateOrderItem(java.lang.String expr, boolean nullable, boolean ascending) Generates an item for an ORDER BY clause, sorting in the required direction, and ensuring that NULL values collate after all non-NULL values.
Dialect.NullCollation	getNullCollation() Returns the rule which determines whether NULL values appear first or last when sorted using ORDER BY.
static boolean	isInfobright(java.sql.DatabaseMetaData databaseMetaData) Detects whether this database is Infobright.
boolean	requiresAliasForFromQuery() Returns whether this Dialect requires subqueries in the FROM clause to have an alias.
boolean	requiresOrderByAlias() Returns true if this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias.
boolean	supportsMultiValueInExpr() Returns true if this dialect supports multi-value IN expressions.

Methods inherited from class mondrian.spi.impl.JdbcDialectImpl

allowsAs, allowsCountDistinct, allowsDdl, allowsDialectSharing, allowsMultipleCountDistinct, allowsMultipleDistinctSqlMeasures, allowsOrderByAlias, allowsSelectNotInGroupBy, caseWhenElse, deduceMaxColumnNameLength, deduceProductVersion, deduceReadOnly, deduceSupportedResultSetStyles, generateInlineForAnsi, generateInlineGeneric, getDatabaseProduct, getMaxColumnNameLength, getProduct, getQuoteIdentifierString, needsExponent, quote, quoteBooleanLiteral, quoteDateLiteral, quoteDateLiteral, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteNumericLiteral, quoteStringLiteral, quoteTimeLiteral, quoteTimestampLiteral, requiresGroupByAlias, requiresUnionOrderByExprToBeInSelectClause, requiresUnionOrderByOrdinal, supportsGroupByExpressions, supportsGroupingSets, supportsOrderByNullsLast, supportsResultSetConcurrency, supportsUnlimitedValueList, toString, toUpper

Methods inherited from class java.lang.Object

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

Field Detail

FACTORY

public static final JdbcDialectFactory FACTORY

Constructor Detail

MySqlDialect

public MySqlDialect(java.sql.Connection connection)
             throws java.sql.SQLException

Creates a MySqlDialect.

Parameters:

connection - Connection

Throws:

java.sql.SQLException

Method Detail

isInfobright

public static boolean isInfobright(java.sql.DatabaseMetaData databaseMetaData)

Detects whether this database is Infobright.

Infobright uses the MySQL driver and appears to be a MySQL instance. The only difference is the presence of the BRIGHTHOUSE engine.

Parameters:

databaseMetaData - Database metadata

Returns:

Whether this is Infobright

deduceProductName

protected java.lang.String deduceProductName(java.sql.DatabaseMetaData databaseMetaData)

Overrides:

deduceProductName in class JdbcDialectImpl

deduceIdentifierQuoteString

protected java.lang.String deduceIdentifierQuoteString(java.sql.DatabaseMetaData databaseMetaData)

Overrides:

deduceIdentifierQuoteString in class JdbcDialectImpl

deduceSupportsSelectNotInGroupBy

protected boolean deduceSupportsSelectNotInGroupBy(java.sql.Connection connection)
                                            throws java.sql.SQLException

Description copied from class: JdbcDialectImpl

Detects whether the database is configured to permit queries that include columns in the SELECT that are not also in the GROUP BY. MySQL is an example of one that does, though this is configurable.

The expectation is that this will not change while Mondrian is running, though some databases (MySQL) allow changing it on the fly.

Overrides:

deduceSupportsSelectNotInGroupBy in class JdbcDialectImpl

Parameters:

connection - The database connection

Returns:

Whether the feature is enabled.

Throws:

java.sql.SQLException

appendHintsAfterFromClause

public void appendHintsAfterFromClause(java.lang.StringBuilder buf,
                                       java.util.Map<java.lang.String,java.lang.String> hints)

Description copied from interface: Dialect

Assembles and returns a string containing any hints that should be appended after the FROM clause in a SELECT statement, based on any hints provided. Any unrecognized or unsupported hints will be ignored.

Specified by:

appendHintsAfterFromClause in interface Dialect

Overrides:

appendHintsAfterFromClause in class JdbcDialectImpl

Parameters:

buf - The Stringbuffer to which the dialect-specific syntax for any relevant table hints may be appended. Must not be null.

hints - A map of table hints provided in the schema definition

requiresAliasForFromQuery

public boolean requiresAliasForFromQuery()

Description copied from interface: Dialect

Returns whether this Dialect requires subqueries in the FROM clause to have an alias.

Specified by:

requiresAliasForFromQuery in interface Dialect

Overrides:

requiresAliasForFromQuery in class JdbcDialectImpl

Returns:

whether dialewct requires subqueries to have an alias

See Also:

Dialect.allowsFromQuery()

allowsFromQuery

public boolean allowsFromQuery()

Description copied from interface: Dialect

Returns whether this Dialect allows a subquery in the from clause, for example

SELECT * FROM (SELECT * FROM t) AS x

Specified by:

allowsFromQuery in interface Dialect

Overrides:

allowsFromQuery in class JdbcDialectImpl

Returns:

whether Dialect allows subquery in FROM clause

See Also:

Dialect.requiresAliasForFromQuery()

allowsCompoundCountDistinct

public boolean allowsCompoundCountDistinct()

Description copied from interface: Dialect

Returns whether this Dialect allows multiple arguments to the COUNT(DISTINCT ...) aggregate function, for example

SELECT COUNT(DISTINCT x, y) FROM t

Specified by:

allowsCompoundCountDistinct in interface Dialect

Overrides:

allowsCompoundCountDistinct in class JdbcDialectImpl

Returns:

whether Dialect allows multiple arguments to COUNT DISTINCT

See Also:

Dialect.allowsCountDistinct(), Dialect.allowsMultipleCountDistinct()

generateInline

public java.lang.String generateInline(java.util.List<java.lang.String> columnNames,
                                       java.util.List<java.lang.String> columnTypes,
                                       java.util.List<java.lang.String[]> valueList)

Description copied from interface: Dialect

Generates a SQL statement to represent an inline dataset.

For example, for Oracle, generates

 SELECT 1 AS FOO, 'a' AS BAR FROM dual
 UNION ALL
 SELECT 2 AS FOO, 'b' AS BAR FROM dual
 

For ANSI SQL, generates:

 VALUES (1, 'a'), (2, 'b')
 

Specified by:

generateInline in interface Dialect

Overrides:

generateInline in class JdbcDialectImpl

Parameters:

columnNames - List of column names

columnTypes - List of column types ("String" or "Numeric")

valueList - List of rows values

Returns:

SQL string

getNullCollation

public Dialect.NullCollation getNullCollation()

Description copied from interface: Dialect

Returns the rule which determines whether NULL values appear first or last when sorted using ORDER BY.

According to the SQL standard, this is implementation-specific. The default behavior is Dialect.NullCollation.POSINF.

Specified by:

getNullCollation in interface Dialect

Overrides:

getNullCollation in class JdbcDialectImpl

Returns:

Rule which determines whether NULL values collate first or last

generateOrderItem

public java.lang.String generateOrderItem(java.lang.String expr,
                                          boolean nullable,
                                          boolean ascending)

Description copied from interface: Dialect

Generates an item for an ORDER BY clause, sorting in the required direction, and ensuring that NULL values collate after all non-NULL values.

By default, generateOrderItem(expr, true) generates "expr ASC" and generateOrderItem(expr, false) generates "expr DESC". But depending on Dialect.getNullCollation() and ascending, there may need to be additional code.

For example, on Oracle, where NULLs collate higher than all other values, generateOrderItem(expr, true) generates "expr ASC" and generateOrderItem(expr, false) generates "expr DESC NULLS LAST".

On MySQL, where NULLs collate lower than all other values, generateOrderItem(expr, true) generates "ISNULL(expr), expr ASC" and generateOrderItem(expr, false) generates "expr DESC".

Specified by:

generateOrderItem in interface Dialect

Overrides:

generateOrderItem in class JdbcDialectImpl

Parameters:

expr - Expression

nullable - Whether expression may have NULL values

ascending - Whether to sort expression ascending

Returns:

Expression modified so that NULL values collate last

requiresOrderByAlias

public boolean requiresOrderByAlias()

Description copied from interface: Dialect

Returns true if this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias.

For example, in such a dialect,

SELECT x FROM t ORDER BY x + y

would be illegal, but

SELECT x, x + y AS z FROM t ORDER BY z

would be legal.

MySQL, DB2 and Ingres are examples of such dialects.

Specified by:

requiresOrderByAlias in interface Dialect

Overrides:

requiresOrderByAlias in class JdbcDialectImpl

Returns:

Whether this Dialect can include expressions in the ORDER BY clause only by adding an expression to the SELECT clause and using its alias

supportsMultiValueInExpr

public boolean supportsMultiValueInExpr()

Description copied from interface: Dialect

Returns true if this dialect supports multi-value IN expressions. E.g., WHERE (col1, col2) IN ((val1a, val2a), (val1b, val2b))

Specified by:

supportsMultiValueInExpr in interface Dialect

Overrides:

supportsMultiValueInExpr in class JdbcDialectImpl

Returns:

true if the dialect supports multi-value IN expressions