org.apache.calcite.sql.dialect

Class MysqlSqlDialect

java.lang.Object

org.apache.calcite.sql.SqlDialect

org.apache.calcite.sql.dialect.MysqlSqlDialect

public class MysqlSqlDialect
extends SqlDialect

A SqlDialect implementation for the MySQL database.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.calcite.sql.SqlDialect

SqlDialect.CalendarPolicy, SqlDialect.Context, SqlDialect.DatabaseProduct, SqlDialect.FakeUtil

Field Summary

Fields

Modifier and Type	Field and Description
static SqlDialect	DEFAULT
static SqlDialect.Context	DEFAULT_CONTEXT
static SqlFunction	ISNULL_FUNCTION MySQL specific function.
static RelDataTypeSystem	MYSQL_TYPE_SYSTEM MySQL type system.

Fields inherited from class org.apache.calcite.sql.SqlDialect

BUILT_IN_OPERATORS_LIST, EMPTY_CONTEXT, identifierEndQuoteString, identifierEscapedQuote, identifierQuoteString, literalEndQuoteString, literalEscapedQuote, literalQuoteString, LOGGER, nullCollation

Constructor Summary

Constructors

Constructor and Description
MysqlSqlDialect(SqlDialect.Context context) Creates a MysqlSqlDialect.

Method Summary

Modifier and Type	Method and Description
@Nullable SqlNode	emulateNullDirection(SqlNode node, boolean nullsFirst, boolean desc) Returns the SqlNode for emulating the null direction for the given field or null if no emulation needs to be done.
SqlDialect.CalendarPolicy	getCalendarPolicy()
@Nullable SqlNode	getCastSpec(RelDataType type) Returns SqlNode for type in "cast(column as type)", which might be different between databases by type name, precision etc.
boolean	requiresAliasForFromItems() Whether a sub-query in the FROM clause must have an alias.
SqlNode	rewriteSingleValueExpr(SqlNode aggCall) Rewrite SINGLE_VALUE into expression based on database variants E.g.
boolean	supportsAggregateFunction(SqlKind kind)
boolean	supportsAliasedValues() Returns whether the dialect supports VALUES in a sub-query with and an "AS t(column, ...)" values to define column names.
boolean	supportsCharSet() Returns whether the dialect supports character set names as part of a data type, for instance VARCHAR(30) CHARACTER SET `ISO-8859-1`.
boolean	supportsGroupByWithRollup() Returns whether this dialect supports "WITH ROLLUP" in the "GROUP BY" clause.
boolean	supportsJoinType(JoinRelType joinType) Returns whether this dialect support the specified type of join.
boolean	supportsNestedAggregations() Returns whether the dialect supports nested aggregations, for instance SELECT SUM(SUM(1)) .
void	unparseCall(SqlWriter writer, SqlCall call, int leftPrec, int rightPrec)
void	unparseOffsetFetch(SqlWriter writer, @Nullable SqlNode offset, @Nullable SqlNode fetch) Converts an offset and fetch into SQL.
void	unparseSqlIntervalQualifier(SqlWriter writer, SqlIntervalQualifier qualifier, RelDataTypeSystem typeSystem) Converts an interval qualifier to a SQL string.

Methods inherited from class org.apache.calcite.sql.SqlDialect

allowsAs, configureParser, configureParser, containsNonAscii, create, defaultNullDirection, emulateJoinTypeForCrossJoin, emulateNullDirectionWithIsNull, getConformance, getDatabaseProduct, getNullCollation, getProduct, getQuotedCasing, getQuoting, getSingleRowTableName, getTypeSystem, getUnquotedCasing, hasImplicitTableAlias, identifierNeedsQuote, isCaseSensitive, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteStringLiteral, quoteStringLiteral, quoteStringLiteralUnicode, quoteTimestampLiteral, supportsAggregateFunctionFilter, supportsApproxCountDistinct, supportsDataType, supportsFunction, supportsGroupByLiteral, supportsGroupByWithCube, supportsImplicitTypeCoercion, supportsOffsetFetch, supportsWindowFunctions, unparseDateTimeLiteral, unparseFetchUsingAnsi, unparseFetchUsingLimit, unparseLimit, unparseOffset, unparseSqlDatetimeArithmetic, unparseSqlIntervalLiteral, unparseTableScanHints, unparseTopN, unquoteStringLiteral

Methods inherited from class java.lang.Object

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

Field Detail

MYSQL_TYPE_SYSTEM

public static final RelDataTypeSystem MYSQL_TYPE_SYSTEM

MySQL type system.

DEFAULT_CONTEXT

public static final SqlDialect.Context DEFAULT_CONTEXT

DEFAULT

public static final SqlDialect DEFAULT

ISNULL_FUNCTION

public static final SqlFunction ISNULL_FUNCTION

MySQL specific function.

Constructor Detail

MysqlSqlDialect

public MysqlSqlDialect(SqlDialect.Context context)

Creates a MysqlSqlDialect.

Method Detail

supportsCharSet

public boolean supportsCharSet()

Description copied from class: SqlDialect

Returns whether the dialect supports character set names as part of a data type, for instance VARCHAR(30) CHARACTER SET `ISO-8859-1`.

Overrides:

supportsCharSet in class SqlDialect

requiresAliasForFromItems

public boolean requiresAliasForFromItems()

Description copied from class: SqlDialect

Whether a sub-query in the FROM clause must have an alias.

For example, in PostgreSQL, this query is legal:

SELECT * FROM (SELECT * FROM Emp) As e

but remove the alias e and it is not:

SELECT * FROM (SELECT * FROM Emp)

In Oracle, both queries are legal.

Overrides:

requiresAliasForFromItems in class SqlDialect

supportsAliasedValues

public boolean supportsAliasedValues()

Description copied from class: SqlDialect

Returns whether the dialect supports VALUES in a sub-query with and an "AS t(column, ...)" values to define column names.

Currently, only Oracle does not. For this, we generate "SELECT v0 AS c0, v1 AS c1 ... UNION ALL ...". We may need to refactor this method when we support VALUES for other dialects.

Overrides:

supportsAliasedValues in class SqlDialect

unparseOffsetFetch

public void unparseOffsetFetch(SqlWriter writer,
                               @Nullable SqlNode offset,
                               @Nullable SqlNode fetch)

Description copied from class: SqlDialect

Converts an offset and fetch into SQL.

At least one of offset and fetch must be provided.

Common options:

• OFFSET offset ROWS FETCH NEXT fetch ROWS ONLY (ANSI standard SQL, Oracle, PostgreSQL, and the default)
• LIMIT fetch OFFSET offset (Apache Hive, MySQL, Redshift)

Overrides:

unparseOffsetFetch in class SqlDialect

Parameters:

writer - Writer

offset - Number of rows to skip before emitting, or null

fetch - Number of rows to fetch, or null

See Also:

SqlDialect.unparseFetchUsingAnsi(SqlWriter, SqlNode, SqlNode), SqlDialect.unparseFetchUsingLimit(SqlWriter, SqlNode, SqlNode)

emulateNullDirection

public @Nullable SqlNode emulateNullDirection(SqlNode node,
                                              boolean nullsFirst,
                                              boolean desc)

Description copied from class: SqlDialect

Returns the SqlNode for emulating the null direction for the given field or null if no emulation needs to be done.

Overrides:

emulateNullDirection in class SqlDialect

Parameters:

node - The SqlNode representing the expression

nullsFirst - Whether nulls should come first

desc - Whether the sort direction is RelFieldCollation.Direction#DESCENDING or RelFieldCollation.Direction#STRICTLY_DESCENDING

Returns:

A SqlNode for null direction emulation or null if not required

supportsAggregateFunction

public boolean supportsAggregateFunction(SqlKind kind)

Overrides:

supportsAggregateFunction in class SqlDialect

supportsNestedAggregations

public boolean supportsNestedAggregations()

Description copied from class: SqlDialect

Returns whether the dialect supports nested aggregations, for instance SELECT SUM(SUM(1)) .

Overrides:

supportsNestedAggregations in class SqlDialect

supportsGroupByWithRollup

public boolean supportsGroupByWithRollup()

Description copied from class: SqlDialect

Returns whether this dialect supports "WITH ROLLUP" in the "GROUP BY" clause.

For instance, in MySQL version 5,

SELECT deptno, job, COUNT(*) AS c FROM emp GROUP BY deptno, job WITH ROLLUP

is equivalent to standard SQL

SELECT deptno, job, COUNT(*) AS c FROM emp GROUP BY ROLLUP(deptno, job) ORDER BY deptno, job

The "WITH ROLLUP" clause was introduced in MySQL and is not standard SQL.

See also SqlDialect.supportsAggregateFunction(SqlKind) applied to SqlKind.ROLLUP, which returns true in MySQL 8 and higher.

Overrides:

supportsGroupByWithRollup in class SqlDialect

getCalendarPolicy

public SqlDialect.CalendarPolicy getCalendarPolicy()

Overrides:

getCalendarPolicy in class SqlDialect

getCastSpec

public @Nullable SqlNode getCastSpec(RelDataType type)

Description copied from class: SqlDialect

Returns SqlNode for type in "cast(column as type)", which might be different between databases by type name, precision etc.

If this method returns null, the cast will be omitted. In the default implementation, this is the case for the NULL type, and therefore CAST(NULL AS <nulltype>) is rendered as NULL.

Overrides:

getCastSpec in class SqlDialect

rewriteSingleValueExpr

public SqlNode rewriteSingleValueExpr(SqlNode aggCall)

Description copied from class: SqlDialect

Rewrite SINGLE_VALUE into expression based on database variants E.g. HSQLDB, MYSQL, ORACLE, etc

Overrides:

rewriteSingleValueExpr in class SqlDialect

unparseCall

public void unparseCall(SqlWriter writer,
                        SqlCall call,
                        int leftPrec,
                        int rightPrec)

Overrides:

unparseCall in class SqlDialect

unparseSqlIntervalQualifier

public void unparseSqlIntervalQualifier(SqlWriter writer,
                                        SqlIntervalQualifier qualifier,
                                        RelDataTypeSystem typeSystem)

Description copied from class: SqlDialect

Converts an interval qualifier to a SQL string. The default implementation returns strings such as INTERVAL '1 2:3:4' DAY(4) TO SECOND(4).

Overrides:

unparseSqlIntervalQualifier in class SqlDialect

supportsJoinType

public boolean supportsJoinType(JoinRelType joinType)

Description copied from class: SqlDialect

Returns whether this dialect support the specified type of join.

Overrides:

supportsJoinType in class SqlDialect