AggregateFunction

A user-defined aggregate function needs to implement this interface. The class must be public and must have a public non-argument constructor.

Please note this interface only has limited support for data types. If you need data types that don't have a corresponding SQL type (for example GEOMETRY), then use the {@link Aggregate} interface.



Methods
void add(Object value)
This method is called once for each row.
void add(Object value) throws SQLException
This method is called once for each row. If the aggregate function is called with multiple parameters, those are passed as array.
Parameters:
value - the value(s) for this row
Object getResult()
This method returns the computed aggregate value.
Object getResult() throws SQLException
This method returns the computed aggregate value.
Returns:
the aggregated value
int getType(int[] inputTypes)
This method must return the SQL type of the method, given the SQL type of the input data.
int getType(int[] inputTypes) throws SQLException
This method must return the SQL type of the method, given the SQL 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.
Parameters:
inputTypes - the SQL type of the parameters, {@link java.sql.Types}
Returns:
the SQL type of the result
void init(Connection conn)
This method is called when the aggregate function is used.
void init(Connection conn) throws SQLException
This method is called when the aggregate function is used. A new object is created for each invocation.
Parameters:
conn - a connection to the database