Class CountAggregateDefinition
- java.lang.Object
-
- org.apache.derby.impl.sql.compile.CountAggregateDefinition
-
- All Implemented Interfaces:
AggregateDefinition
class CountAggregateDefinition extends java.lang.Object implements AggregateDefinition
Definition for the COUNT()/COUNT(*) aggregates.
-
-
Constructor Summary
Constructors Constructor Description CountAggregateDefinition()
Niladic constructor.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description DataTypeDescriptor
getAggregator(DataTypeDescriptor inputType, java.lang.StringBuffer aggregatorClass)
Determines the result datatype.
-
-
-
Method Detail
-
getAggregator
public final DataTypeDescriptor getAggregator(DataTypeDescriptor inputType, java.lang.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:
TypeDescriptor
-
-