Package org.datanucleus.store.rdbms.sql.method

Class MapKeyMethod

java.lang.Object

org.datanucleus.store.rdbms.sql.method.MapKeyMethod

All Implemented Interfaces:

SQLMethod

public class MapKeyMethod
extends Object
implements SQLMethod

Method for evaluating KEY({mapExpr}). Returns an ObjectExpression representing the key mapping.

Constructor Summary

Constructors

Constructor	Description
MapKeyMethod()

Method Summary

Modifier and Type	Method	Description
protected SQLExpression	getAsJoin(SQLStatement parentStmt, MapExpression mapExpr)	Implementation of KEY(mapExpr) using a join to the table representing the map, and returning an expression for the key.
protected SQLExpression	getAsSubquery(SQLStatement stmt, MapExpression mapExpr)	Implementation of KEY(mapExpr) using a subquery on the table representing the map.
SQLExpression	getExpression(SQLStatement stmt, SQLExpression expr, List<SQLExpression> args)	Return the expression for this SQL function.

Methods inherited from class java.lang.Object

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

Constructor Detail

MapKeyMethod

public MapKeyMethod()

Method Detail

getExpression

public SQLExpression getExpression(SQLStatement stmt,
                                   SQLExpression expr,
                                   List<SQLExpression> args)

Description copied from interface: SQLMethod

Return the expression for this SQL function.

Specified by:

getExpression in interface SQLMethod

Parameters:

stmt - SQLStatement that this expression is for

expr - The expression that it is invoked on

args - Arguments passed in

Returns:

The SQL expression using the SQL function

getAsJoin

protected SQLExpression getAsJoin(SQLStatement parentStmt,
                                  MapExpression mapExpr)

Implementation of KEY(mapExpr) using a join to the table representing the map, and returning an expression for the key.

Parameters:

parentStmt - The parent SQL statement

mapExpr - The map expression

Returns:

The value expression

getAsSubquery

protected SQLExpression getAsSubquery(SQLStatement stmt,
                                      MapExpression mapExpr)

Implementation of KEY(mapExpr) using a subquery on the table representing the map.

Parameters:

stmt - SQLStatement

mapExpr - The map expression

Returns:

The value expression