MySQL表鎖

在mysql中的表鎖，LOCK TABLE t READ;  用讀鎖鎖表，會阻塞其他事務修改表資料
===================================================================
####Session 1
mysql> select * from t;
+------+------+
| id   | name |
+------+------+
|    1 | WW   |
|    2 | SS   |
|    3 | VV   |
+------+------+
3 rows in set (0.00 sec)

####讀鎖-鎖表t
mysql> LOCK TABLE t READ;

####Session 2,可以讀取資料
mysql> select * from t where id=1;
+------+------+
| id   | name |
+------+------+
|    1 | WW   |
+------+------+
1 row in set (0.00 sec)

####Session 2, insert資料被阻塞
mysql> insert into t values(4,'LL');

####Session 1, 解除讀鎖-鎖表t
mysql> UNLOCK table;
Query OK, 0 rows affected (0.00 sec)

在mysql中的表鎖，LOCK TABLE t WRITE; 用寫鎖鎖表，會阻塞其他事務讀和寫
===================================================================
####Session 1
mysql> select * from t;
+------+------+
| id   | name |
+------+------+
|    1 | WW   |
|    2 | SS   |
|    3 | VV   |
+------+------+
3 rows in set (0.00 sec)

####Session 1,寫鎖-鎖表t
mysql> LOCK TABLE t WRITE;

####Session 2,讀取資料被阻塞
mysql> select * from t where id=1;

####Session 2, insert資料被阻塞
mysql> insert into t values(4,'LL');

####Session 1, 解除讀鎖-鎖表t
mysql> UNLOCK table;
Query OK, 0 rows affected (0.00 sec)
=================================================================

--待續