MySQL默认隔离级别REPEATABLE-READ并没有解决幻读问题

MySQL [test]> select * from t1;

+------+

| id   |

+------+

|    1 |

|    2 |

|    3 |

|    4 |

+------+

4 rows in set (0.000 sec)

MySQL [test]> select * from t1;

+------+

| id   |

+------+

|    1 |

|    2 |

|    3 |

|    4 |

+------+

4 rows in set (0.000 sec)

MySQL [test]> begin;

Query OK, 0 rows affected (0.000 sec)

注：开启事务一

MySQL [test]> begin;

Query OK, 0 rows affected (0.000 sec)

注：开启事务二

MySQL [test]> insert into t1 values(5);

Query OK, 1 row affected (0.000 sec)

MySQL [test]> select * from t1;

+------+

| id   |

+------+

|    1 |

|    2 |

|    3 |

|    4 |

|    5 |

+------+

5 rows in set (0.000 sec)

注：插入一条数据5

MySQL [test]> select * from t1;

+------+

| id   |

+------+

|    1 |

|    2 |

|    3 |

|    4 |

+------+

4 rows in set (0.000 sec)

注：因会话一未提交，所以在会话二事务里是看不见更改后的结果的

MySQL [test]> commit;

Query OK, 0 rows affected (0.002 sec)

注：会话一执行事务提交

MySQL [test]> select * from t1;

+------+

| id   |

+------+

|    1 |

|    2 |

|    3 |

|    4 |

+------+

4 rows in set (0.000 sec)

MySQL [test]> update t1 set id = id+10;

Query OK, 5 rows affected (0.001 sec)

Rows matched: 5  Changed: 5  

Warnings: 0

注：执行全表更新，id+10

MySQL [test]> select * from t1;

+------+

| id   |

+------+

|   11 |

|   12 |

|   13 |

|   14 |

|   15 |

+------+

5 rows in set (0.000 sec)

注：当再次查看时，此时发现有5条数据被更改，产生幻读

MySQL [test]> select version();

+-----------+

| version() |

+-----------+

| 8.0.21    |

+-----------+

1 row in set (0.000 sec)