H2 - 如何创建一个数据库触发器,将一行更改记录到另一行 table?
H2 - How to create a database trigger that log a row change to another table?
如何创建一个数据库触发器来记录 H2 中对另一行的更改 table?
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;
声明此触发器:
CREATE TRIGGER my_trigger
BEFORE UPDATE
ON my_table
FOR EACH ROW
CALL "com.example.MyTrigger"
使用 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 {}
}
使用 jOOQ 实现触发器:
由于您在问题中添加了 jOOQ 标签,我怀疑这个备选方案也可能相关。您当然可以在 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();
}
Lukas Eder 回答的简化版:
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
}
}
如何创建一个数据库触发器来记录 H2 中对另一行的更改 table?
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;
声明此触发器:
CREATE TRIGGER my_trigger
BEFORE UPDATE
ON my_table
FOR EACH ROW
CALL "com.example.MyTrigger"
使用 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 {}
}
使用 jOOQ 实现触发器:
由于您在问题中添加了 jOOQ 标签,我怀疑这个备选方案也可能相关。您当然可以在 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();
}
Lukas Eder 回答的简化版:
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
}
}