会话A和会话B
update test set value = value + 1 where id = 1;
select value from test where id = 1;
```sql

### 会话B查询值
```sql
select value from test where id = 1;
```sql

### 会话B修改值
```sql
update test set value = value + 1 where id = 1;
会话B被阻塞
会话B修改成功
原文:https://www.cnblogs.com/huisunan/p/15186504.html