org.datanucleus.store.rdbms.sql.method

Class AvgFunction

java.lang.Object

org.datanucleus.store.rdbms.sql.method.AbstractSQLMethod

org.datanucleus.store.rdbms.sql.method.SimpleNumericAggregateMethod

org.datanucleus.store.rdbms.sql.method.AvgFunction

All Implemented Interfaces:

SQLMethod

Direct Known Subclasses:

AvgWithCastFunction

public class AvgFunction
extends SimpleNumericAggregateMethod

Expression handler to invoke the SQL AVG aggregation function. For use in evaluating AVG({expr}) where the RDBMS supports this function. Returns a NumericExpression "AVG({numericExpr})".

Field Summary

Fields inherited from class org.datanucleus.store.rdbms.sql.method.AbstractSQLMethod

clr, exprFactory, stmt

Constructor Summary

Constructors

Constructor and Description
AvgFunction()

Method Summary

Modifier and Type	Method and Description
protected SQLExpression	getAggregateExpression(List args, JavaTypeMapping m)
protected Class	getClassForMapping()
SQLExpression	getExpression(SQLExpression expr, List args) Return the expression for this SQL function.
protected String	getFunctionName()

Methods inherited from class org.datanucleus.store.rdbms.sql.method.AbstractSQLMethod

getMappingForClass, setStatement

Methods inherited from class java.lang.Object

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

Constructor Detail

AvgFunction

public AvgFunction()

Method Detail

getFunctionName

protected String getFunctionName()

Specified by:

getFunctionName in class SimpleNumericAggregateMethod

getExpression

public SQLExpression getExpression(SQLExpression expr,
                                   List args)

Description copied from interface: SQLMethod

Return the expression for this SQL function.

Specified by:

getExpression in interface SQLMethod

Overrides:

getExpression in class SimpleNumericAggregateMethod

Parameters:

expr - The expression that it is invoked on

args - Arguments passed in

Returns:

The SQL expression using the SQL function

getAggregateExpression

protected SQLExpression getAggregateExpression(List args,
                                               JavaTypeMapping m)

getClassForMapping

protected Class getClassForMapping()

Specified by:

getClassForMapping in class SimpleNumericAggregateMethod