Mysql：lock tables tb_nm 之后如何再得到tb_nm的状态？

Question

我在一个程序中要lock table tb_nm， 在这之前我想要知道另外一个程序或者服务对没对这个表（tb_nm）进行lock，
请问我如何得到该表的状态来决定我自己是否lock tb_nm？

Answer 1

Try to analyze the result of show processlist.

Answer 2

mysql> use t_girl
Database changed
mysql> show open tables;
+----------+---------------+--------+-------------+
| Database | Table         | In_use | Name_locked |
+----------+---------------+--------+-------------+
| t_girl   | slave         |      0 |           0 | 
| mysql    | help_keyword  |      0 |           0 | 
| mysql    | help_category |      0 |           0 | 
| mysql    | help_relation |      0 |           0 | 
| t_girl   | t1            |      0 |           0 | 
| mysql    | help_topic    |      0 |           0 | 
| mysql    | user          |      0 |           0 | 
+----------+---------------+--------+-------------+
7 rows in set (0.00 sec)mysql> lock tables t1 as a read;
Query OK, 0 rows affected (0.00 sec)mysql> show open tables;
+----------+---------------+--------+-------------+
| Database | Table         | In_use | Name_locked |
+----------+---------------+--------+-------------+
| t_girl   | slave         |      0 |           0 | 
| mysql    | help_keyword  |      0 |           0 | 
| mysql    | help_category |      0 |           0 | 
| mysql    | help_relation |      0 |           0 | 
| t_girl   | t1            |      1 |           0 | 
| mysql    | help_topic    |      0 |           0 | 
| mysql    | user          |      0 |           0 | 
+----------+---------------+--------+-------------+
7 rows in set (0.00 sec)mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)mysql> show open tables;
+----------+---------------+--------+-------------+
| Database | Table         | In_use | Name_locked |
+----------+---------------+--------+-------------+
| t_girl   | slave         |      0 |           0 | 
| mysql    | help_keyword  |      0 |           0 | 
| mysql    | help_category |      0 |           0 | 
| mysql    | help_relation |      0 |           0 | 
| t_girl   | t1            |      0 |           0 | 
| mysql    | help_topic    |      0 |           0 | 
| mysql    | user          |      0 |           0 | 
+----------+---------------+--------+-------------+
7 rows in set (0.00 sec)