Class CountAggregateDefinition
java.lang.Object
org.apache.derby.impl.sql.compile.CountAggregateDefinition
- All Implemented Interfaces:
AggregateDefinition
Definition for the COUNT()/COUNT(*) aggregates.
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionfinal DataTypeDescriptor
getAggregator
(DataTypeDescriptor inputType, StringBuffer aggregatorClass) Determines the result datatype.
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Constructor Details
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CountAggregateDefinition
public CountAggregateDefinition()Niladic constructor. Does nothing. For ease Of use, only.
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Method Details
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getAggregator
public final DataTypeDescriptor getAggregator(DataTypeDescriptor inputType, StringBuffer aggregatorClass) Determines the result datatype. We can run count() on anything, and it always returns a INTEGER (java.lang.Integer).- Specified by:
getAggregator
in interfaceAggregateDefinition
- Parameters:
inputType
- the input type, either a user type or a java.lang objectaggregatorClass
- output parameter, filled in with the class name that implements com.ibm.db2j.aggregates.Aggregator- Returns:
- the output Class (null if cannot operate on value expression of this type.
- See Also:
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