CountAggregateDefinition (Apache Derby V10.14 Internals)

Skip navigation links

All Classes

SEARCH:

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

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.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - CountAggregateDefinition
```
public CountAggregateDefinition()
```
    Niladic constructor. Does nothing. For ease Of use, only.
- 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 interface AggregateDefinition
    
    Parameters:
    
    inputType - the input type, either a user type or a java.lang object
    
    aggregatorClass - 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

Skip navigation links

Built on Wed 2018-05-16 16:01:03+0000, from revision ???

All Classes

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

Apache Derby V10.14 Internals - Copyright © 2004,2018 The Apache Software Foundation. All Rights Reserved.