H2 - 如何创建将行更改记录到另一个表的数据库触发器？

Posted 2021-05-03

如何在H2中创建将行更改记录到另一个表的数据库触发器？

在mysql中，这可以很容易地完成：

CREATE TRIGGER `trigger` BEFORE UPDATE ON `table`
  FOR EACH ROW BEGIN
    INSERT INTO `log`
    (
      `field1`
      `field2`,
      ...
    )
    VALUES
    (
      NEW.`field1`,
      NEW.`field2`,
      ...
    ) ;
    END;

答案

声明此触发器：

CREATE TRIGGER my_trigger
BEFORE UPDATE
ON my_table
FOR EACH ROW
CALL "com.example.MyTrigger"

Implementing the trigger with Java/JDBC:

public class MyTrigger implements Trigger {

    @Override
    public void init(Connection conn, String schemaName, 
                     String triggerName, String tableName, boolean before, int type)
    throws SQLException {}

    @Override
    public void fire(Connection conn, Object[] oldRow, Object[] newRow)
    throws SQLException {
        try (PreparedStatement stmt = conn.prepareStatement(
            "INSERT INTO log (field1, field2, ...) " +
            "VALUES (?, ?, ...)")
        ) {
            stmt.setObject(1, newRow[0]);
            stmt.setObject(2, newRow[1]);
            ...

            stmt.executeUpdate();
        }
    }

    @Override
    public void close() throws SQLException {}

    @Override
    public void remove() throws SQLException {}
}

Implementing the trigger with jOOQ:

由于您在问题中添加了jOOQ标记，我怀疑这种替代方案也可能是相关的。你当然可以在H2触发器中使用jOOQ：

    @Override
    public void fire(Connection conn, Object[] oldRow, Object[] newRow)
    throws SQLException {
        DSL.using(conn)
           .insertInto(LOG, LOG.FIELD1, LOG.FIELD2, ...)
           .values(LOG.FIELD1.getDataType().convert(newRow[0]), 
                   LOG.FIELD2.getDataType().convert(newRow[1]), ...)
           .execute();
    }