http://www.h2database.com: H2 Database Engine
  • Thomas Mueller 
/*
 * Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
 * and the EPL 1.0 (http://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.

/**
 * A class that implements this interface can be used as a trigger.
 */
public interface Trigger {

    
The trigger is called for INSERT statements.

/**
     * The trigger is called for INSERT statements.
     */
    int INSERT = 1;

    
The trigger is called for UPDATE statements.

/**
     * The trigger is called for UPDATE statements.
     */
    int UPDATE = 2;

    
The trigger is called for DELETE statements.

/**
     * The trigger is called for DELETE statements.
     */
    int DELETE = 4;

    
The trigger is called for SELECT statements.

/**
     * 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).

Params:
  • conn – a connection to the database (a system connection)
  • schemaName – the name of the schema
  • triggerName – the name of the trigger used in the CREATE TRIGGER
           statement
  • tableName – the name of the table
  • before – whether the fire method is called before or after the
           operation is performed
  • type – the operation type: INSERT, UPDATE, DELETE, SELECT, or a
           combination (this parameter is a bit field)
/**
     * 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)
     */
    void init(Connection conn, String schemaName, String triggerName,
            String tableName, boolean before, int type) throws SQLException;

    
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.


The row arrays contain all columns of the table, in the same order
as defined in the table.




The trigger itself may change the data in the newRow array.



Params:
  • conn – a connection to the database
  • oldRow – the old row, or null if no old row is available (for
           INSERT)
  • newRow – the new row, or null if no new row is available (for
           DELETE)
Throws:
/**
     * 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.

/**
     * 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.
     */
    void close() throws SQLException;

    
This method is called when the trigger is dropped.

/**
     * This method is called when the trigger is dropped.
     */
    void remove() throws SQLException;

}