Mysql默認的隔離級別是：
(mysql@localhost) [fandb]> select @@tx_isolation;
+-----------------+
| @@tx_isolation |
+-----------------+
| REPEATABLE-READ |
+-----------------+session A:
(mysql@localhost) [fandb]> begin;
Query OK, 0 rows affected (0.00 sec)
(mysql@localhost) [fandb]> update per1 set name='fan1' where id=1
-> ;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
(mysql@localhost) [fandb]> select * from per1 limit 1;
+----+------+
| id | name |
+----+------+
| 1 | fan1 |
+----+------+
1 row in set (0.00 sec)
A會話更新一行session B:
(mysql@localhost) [fandb]> begin;
Query OK, 0 rows affected (0.00 sec)
(mysql@localhost) [fandb]> select * from per1 limit 1;
+----+------+
| id | name |
+----+------+
| 1 | fan |
+----+------+
1 row in set (0.00 sec)
此時在B開始事務并查詢，id=1的name列并沒有變化session A:
(mysql@localhost) [fandb]> commit;
Query OK, 0 rows affected (0.00 sec)
接著A會話提交session B:
(mysql@localhost) [fandb]> select * from per1 limit 1;
+----+------+
| id | name |
+----+------+
| 1 | fan |
+----+------+
1 row in set (0.00 sec)
在去B會話查詢，還是沒有變化(mysql@localhost) [fandb]> commit;
Query OK, 0 rows affected (0.00 sec)
(mysql@localhost) [fandb]> select * from per1 limit 1;
+----+------+
| id | name |
+----+------+
| 1 | fan1 |
+----+------+
1 row in set (0.00 sec)
只有當B會話事務結束，再次查詢記錄才會變化聲明：本網頁內容旨在傳播知識，若有侵權等問題請及時與本網聯系，我們將在第一時間刪除處理。TEL:177 7030 7066 E-MAIL:11247931@qq.com
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