Class UserAggregate.AggregateWrapper

java.lang.Object

org.h2.schema.UserAggregate.AggregateWrapper

All Implemented Interfaces:

Aggregate

Enclosing class:

UserAggregate

private static class UserAggregate.AggregateWrapper
extends Object
implements Aggregate

Wrap AggregateFunction in order to behave as Aggregate

Field Summary

Fields

Modifier and Type	Field	Description
private final AggregateFunction	aggregateFunction

Constructor Summary

Constructors

Constructor	Description
AggregateWrapper(AggregateFunction aggregateFunction)

Method Summary

Modifier and Type	Method	Description
void	add(Object value)	This method is called once for each row.
int	getInternalType(int[] inputTypes)	This method must return the H2 data type, Value, of the aggregate function, given the H2 data type of the input data.
Object	getResult()	This method returns the computed aggregate value.
void	init(Connection conn)	This method is called when the aggregate function is used.

Methods inherited from class Object

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

Field Details

aggregateFunction

private final AggregateFunction aggregateFunction

Constructor Details

AggregateWrapper

AggregateWrapper(AggregateFunction aggregateFunction)

Method Details

init

public void init(Connection conn)
          throws SQLException

Description copied from interface: Aggregate

This method is called when the aggregate function is used. A new object is created for each invocation.

Specified by:

init in interface Aggregate

Parameters:

conn - a connection to the database

Throws:

SQLException - on SQL exception

getInternalType

public int getInternalType(int[] inputTypes)
                    throws SQLException

Description copied from interface: Aggregate

This method must return the H2 data type, Value, of the aggregate function, given the H2 data type of the input data. The method should check here if the number of parameters passed is correct, and if not it should throw an exception.

Specified by:

getInternalType in interface Aggregate

Parameters:

inputTypes - the H2 data type of the parameters,

Returns:

the H2 data type of the result

Throws:

SQLException - if the number/type of parameters passed is incorrect

add

public void add(Object value)
         throws SQLException

Description copied from interface: Aggregate

This method is called once for each row. If the aggregate function is called with multiple parameters, those are passed as array.

Specified by:

add in interface Aggregate

Parameters:

value - the value(s) for this row

Throws:

SQLException - on failure

getResult

public Object getResult()
                 throws SQLException

Description copied from interface: Aggregate

This method returns the computed aggregate value. This method must preserve previously added values and must be able to reevaluate result if more values were added since its previous invocation.

Specified by:

getResult in interface Aggregate

Returns:

the aggregated value

Throws:

SQLException - on failure