2024年1月25日发(作者：)

# SESSION1# 问题1：SESSION1为mylock表加了读锁，可以读mylock表！mysql> SELECT * FROM `mylock`;+----+----------+| id | name |+----+----------+| 1 | ZhangSan || 2 | LiSi || 3 | WangWu || 4 | ZhaoLiu |+----+----------+4 rows in set (0.00 sec)# 问题2：SESSION1为mylock表加了读锁，不可以修改mylock表！mysql> UPDATE `mylock` SET `name` = 'abc' WHERE `id` = 1;ERROR 1099 (HY000): Table 'mylock' was locked with a READ lock and can't be updated# 问题3：SESSION1为mylock表加了读锁，不可以读其他的表！mysql> SELECT * FROM `book`;ERROR 1100 (HY000): Table 'book' was not locked with LOCK TABLES# SESSION2# 问题1：SESSION1为mylock表加了读锁，SESSION2可以读mylock表！mysql> SELECT * FROM `mylock`;+----+----------+| id | name |+----+----------+| 1 | ZhangSan || 2 | LiSi || 3 | WangWu || 4 | ZhaoLiu |+----+----------+4 rows in set (0.00 sec)# 问题2：SESSION1为mylock表加了读锁，SESSION2修改mylock表会被阻塞，需要等待SESSION1释放mylock表！mysql> UPDATE `mylock` SET `name` = 'abc' WHERE `id` = 1;^C^C -- query abortedERROR 1317 (70100): Query execution was interrupted# 问题3：SESSION1为mylock表加了读锁，SESSION2可以读其他表！mysql> SELECT * FROM `book`;+--------+------+| bookid | card |+--------+------+| 1 | 1 || 7 | 4 || 8 | 4 || 9 | 5 || 5 | 6 || 17 | 6 || 15 | 8 |+--------+------+24 rows in set (0.00 sec)16.4.写锁案例1、打开两个会话，SESSION1为mylock表添加写锁。

Master_SSL_Crl:

Master_SSL_Crlpath:

Retrieved_Gtid_Set:

Executed_Gtid_Set:

Auto_Position: 0 Replicate_Rewrite_DB:

Channel_Name:

Master_TLS_Version:

1 row in set (0.00 sec)