org.apache.openjpa.jdbc.kernel.exps
Class Count

java.lang.Object
  org.apache.openjpa.jdbc.kernel.exps.AbstractVal
      org.apache.openjpa.jdbc.kernel.exps.UnaryOp
          org.apache.openjpa.jdbc.kernel.exps.Count

All Implemented Interfaces:

Serializable, Val, Value

 class Count
extends UnaryOp

Count non-null values.

Author:

Abe White

Field Summary

Fields inherited from class org.apache.openjpa.jdbc.kernel.exps.AbstractVal

FALSE, TRUE

Fields inherited from interface org.apache.openjpa.jdbc.kernel.exps.Val

ABS_VAL, ARGS_VAL, CMP_EQUAL, COALESCE_VAL, CONCAT_VAL, FORCE_OUTER, GENERALCASE_VAL, INDEXOF_VAL, JOIN_REL, LENGTH_VAL, LOCATE_VAL, LOWER_VAL, MATH_VAL, NULL_CMP, NULLIF_VAL, SIMPLECASE_VAL, SQRT_VAL, SUBSTRING_VAL, TRIM_VAL, UPPER_VAL, VAL, WHENCONDITION_VAL, WHENSCALAR_VAL

Constructor Summary

Count(Val val)
Constructor.

Method Summary

void	appendTo(Select sel, ExpContext ctx, ExpState state, SQLBuffer sql, int index) Overrides SQL formation by replacing COUNT(column) by COUNT(*) when specific conditions are met and DBDictionary configuration useWildCardForCount is set.
protected String	getOperator() Return the name of this operator.
protected Class	getType(Class c) Return the type of this value based on the argument type.
ExpState	initialize(Select sel, ExpContext ctx, int flags) Initialize the value.
boolean	isAggregate() Return true if this value is an aggregate.
boolean	isCountDistinctMultiCols()

Methods inherited from class org.apache.openjpa.jdbc.kernel.exps.UnaryOp

acceptVisit, calculateValue, getMetaData, getNoParen, getType, getValue, groupBy, initializeValue, length, load, orderBy, select, selectColumns, setImplicitType, setMetaData

Methods inherited from class org.apache.openjpa.jdbc.kernel.exps.AbstractVal

appendIndex, appendIsEmpty, appendIsNotEmpty, appendIsNotNull, appendIsNull, appendSize, appendType, getAlias, getId, getName, getPath, getSelectAs, isVariable, isXPath, setAlias, toDataStoreValue

Methods inherited from class java.lang.Object

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

Constructor Detail

Count

public Count(Val val)

Constructor. Provide the value to operate on.

Method Detail

initialize

public ExpState initialize(Select sel,
                           ExpContext ctx,
                           int flags)

Description copied from interface: Val

Initialize the value. This method should recursively initialize any sub-values.

Specified by:

initialize in interface Val

Overrides:

initialize in class UnaryOp

getType

protected Class getType(Class c)

Description copied from class: UnaryOp

Return the type of this value based on the argument type. Returns the argument type by default.

Overrides:

getType in class UnaryOp

getOperator

protected String getOperator()

Description copied from class: UnaryOp

Return the name of this operator.

Specified by:

getOperator in class UnaryOp

isAggregate

public boolean isAggregate()

Description copied from interface: Value

Return true if this value is an aggregate.

Specified by:

isAggregate in interface Value

Overrides:

isAggregate in class AbstractVal

isCountDistinctMultiCols

public boolean isCountDistinctMultiCols()

appendTo

public void appendTo(Select sel,
                     ExpContext ctx,
                     ExpState state,
                     SQLBuffer sql,
                     int index)

Overrides SQL formation by replacing COUNT(column) by COUNT(*) when specific conditions are met and DBDictionary configuration useWildCardForCount is set.

Specified by:

appendTo in interface Val

Overrides:

appendTo in class UnaryOp