事务
savepoint 保存点
rollback to 回滚
开启一个事务需要将SQL命令用BEGIN和COMMIT命令包围起来
BEGIN; UPDATE accounts SET balance = balance - 100.00 WHERE name = 'Alice'; SAVEPOINT my_savepoint; UPDATE accounts SET balance = balance + 100.00 WHERE name = 'Bob'; -- oops ... forget that and use Wally's account ROLLBACK TO my_savepoint; UPDATE accounts SET balance = balance + 100.00 WHERE name = 'Wally'; COMMIT;