h2-如何创建一个数据库触发器,将行更改记录到另一个表中?

gijlo24d  于 2021-06-18  发布在  Mysql
关注(0)|答案(2)|浏览(519)

如何创建将行更改记录到h2中另一个表的数据库触发器?
在mysql中,这很容易做到:

CREATE TRIGGER `trigger` BEFORE UPDATE ON `table`
  FOR EACH ROW BEGIN
    INSERT INTO `log`
    (
      `field1`
      `field2`,
      ...
    )
    VALUES
    (
      NEW.`field1`,
      NEW.`field2`,
      ...
    ) ;
    END;
sz81bmfz

sz81bmfz1#

lukas eder回答的简短版本:

CREATE TRIGGER my_trigger
BEFORE UPDATE
ON my_table
FOR EACH ROW
CALL "com.example.MyTrigger"
public class MyTrigger extends TriggerAdapter {

    @Override
    public void fire(Connection conn, ResultSet oldRow, ResultSet newRow) throws SQLException {
        // mannipulate the rows here by using the methods on the oldRow and newRow objects
    }
}
xyhw6mcr

xyhw6mcr2#

声明此触发器:

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

用java/jdbc实现触发器:

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 {}
}

用jooq实现触发器:

既然您在问题中添加了jooq标记,我怀疑这个替代方法也可能相关。当然,您可以在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();
    }

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