# 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