/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.api;
import java.sql.Connection;
import java.sql.SQLException;
/**
* A class that implements this interface can be used as a trigger.
*/
public interface Trigger {
/**
* The trigger is called for INSERT statements.
*/
int INSERT = 1;
/**
* The trigger is called for UPDATE statements.
*/
int UPDATE = 2;
/**
* The trigger is called for DELETE statements.
*/
int DELETE = 4;
/**
* The trigger is called for SELECT statements.
*/
int SELECT = 8;
/**
* This method is called by the database engine once when initializing the
* trigger. It is called when the trigger is created, as well as when the
* database is opened. The type of operation is a bit field with the
* appropriate flags set. As an example, if the trigger is of type INSERT
* and UPDATE, then the parameter type is set to (INSERT | UPDATE).
*
* @param conn a connection to the database (a system connection)
* @param schemaName the name of the schema
* @param triggerName the name of the trigger used in the CREATE TRIGGER
* statement
* @param tableName the name of the table
* @param before whether the fire method is called before or after the
* operation is performed
* @param type the operation type: INSERT, UPDATE, DELETE, SELECT, or a
* combination (this parameter is a bit field)
* @throws SQLException on SQL exception
*/
default void init(Connection conn, String schemaName, String triggerName,
String tableName, boolean before, int type) throws SQLException {
// Does nothing by default
}
/**
* This method is called for each triggered action. The method is called
* immediately when the operation occurred (before it is committed). A
* transaction rollback will also rollback the operations that were done
* within the trigger, if the operations occurred within the same database.
* If the trigger changes state outside the database, a rollback trigger
* should be used.
* <p>
* The row arrays contain all columns of the table, in the same order
* as defined in the table.
* </p>
* <p>
* The trigger itself may change the data in the newRow array.
* </p>
*
* @param conn a connection to the database
* @param oldRow the old row, or null if no old row is available (for
* INSERT)
* @param newRow the new row, or null if no new row is available (for
* DELETE)
* @throws SQLException if the operation must be undone
*/
void fire(Connection conn, Object[] oldRow, Object[] newRow)
throws SQLException;
/**
* This method is called when the database is closed.
* If the method throws an exception, it will be logged, but
* closing the database will continue.
*
* @throws SQLException on SQL exception
*/
default void close() throws SQLException {
// Does nothing by default
}
/**
* This method is called when the trigger is dropped.
*
* @throws SQLException on SQL exception
*/
default void remove() throws SQLException {
// Does nothing by default
}
}