Class CountFunction
- java.lang.Object
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- org.datanucleus.store.rdbms.sql.method.CountFunction
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- All Implemented Interfaces:
SQLMethod
public class CountFunction extends java.lang.Object implements SQLMethod
Expression handler to invoke the SQL COUNT aggregation function. For use in evaluating COUNT({expr}) where the RDBMS supports this function. Returns a NumericExpression "COUNT({numericExpr})".
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Constructor Summary
Constructors Constructor Description CountFunction()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description SQLExpression
getExpression(SQLStatement stmt, SQLExpression expr, java.util.List<SQLExpression> args)
Return the expression for this SQL function.protected java.lang.String
getFunctionName()
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Method Detail
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getFunctionName
protected java.lang.String getFunctionName()
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getExpression
public SQLExpression getExpression(SQLStatement stmt, SQLExpression expr, java.util.List<SQLExpression> args)
Description copied from interface:SQLMethod
Return the expression for this SQL function.- Specified by:
getExpression
in interfaceSQLMethod
- Parameters:
stmt
- SQLStatement that this expression is forexpr
- The expression that it is invoked onargs
- Arguments passed in- Returns:
- The SQL expression using the SQL function
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