數據庫事務處理之排他鎖   排他鎖  www.2cto.com   下面做作一個實驗，驗證鎖的效果 終端一,首先進入事務狀態然後運行下面語句   mysql> begin; Query OK, 0 rows affected (0.00 sec)   mysql> select * from t1 where id='3' for update; +----+--------+---------------------+---------------------+ | id | name   | ctime               | mtime               | +----+--------+---------------------+---------------------+ |  3 | test   | 0000-00-00 00:00:00 | 2013-01-14 13:05:41 | +----+--------+---------------------+---------------------+ 1 row in set (0.00 sec)   終端二, 查詢表中數據   mysql> select * from t1; +----+--------+---------------------+---------------------+ | id | name   | ctime               | mtime               | +----+--------+---------------------+---------------------+ |  1 | neo    | 0000-00-00 00:00:00 | 2013-01-14 13:00:00 | |  2 | zen    | 0000-00-00 00:00:00 | 2013-01-14 13:00:43 | |  3 | test   | 0000-00-00 00:00:00 | 2013-01-14 13:05:41 | +----+--------+---------------------+---------------------+ 3 rows in set (0.00 sec)   增加“for update”查詢非鎖定記錄  www.2cto.com     mysql> select * from t1 where id=2 for update; +----+------+---------------------+---------------------+ | id | name | ctime               | mtime               | +----+------+---------------------+---------------------+ |  2 | zen  | 0000-00-00 00:00:00 | 2013-01-14 13:00:43 | +----+------+---------------------+---------------------+ 1 row in set (0.00 sec)   查詢被鎖定記錄   mysql> select * from t1 where id=3 for update; ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction   查詢所有記錄，因為記錄中包含了id=3那條，所以也不允許查詢。   mysql> select * from t1 for update; ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction   測試修改記錄   mysql> UPDATE `t1` SET `name`='testaa' WHERE  `id`=3; ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction   提示 在沒有出現ERROR 1205 (HY000)的這段時間，只要終端一中執行commit,rollback.終端二中的語句就會運行。