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mysql> select id,avatar from tf_user;
+----+--------------+
| id | avatar |
+----+--------------+
| 1 | avatar_1.png |
| 2 | avatar_6.png |
| 3 | avatar_1.png |
| 4 | avatar_5.png |
| 5 | avatar_5.png |
| 6 | avatar_4.png |
| 7 | avatar_6.png |
| 8 | avatar_3.png |
| 9 | avatar_4.png |
| 10 | avatar_1.png |
| 11 | avatar_5.png |
| 12 | avatar_1.png |
+----+--------------+
12 rows in set (0.01 sec)
mysql> update tf_user set avatar = concat("chongwu_",avatar); //这里用“+”是数学逻辑运算符号;用php中的".",链接字符串也是不行的；
Query OK, 12 rows affected (0.01 sec)
Rows matched: 12 Changed: 12 Warnings: 0
mysql> select id,avatar from tf_user;
+----+----------------------+
| id | avatar |
+----+----------------------+
| 1 | chongwu_avatar_1.png |
| 2 | chongwu_avatar_6.png |
| 3 | chongwu_avatar_1.png |
| 4 | chongwu_avatar_5.png |
| 5 | chongwu_avatar_5.png |
| 6 | chongwu_avatar_4.png |
| 7 | chongwu_avatar_6.png |
| 8 | chongwu_avatar_3.png |
| 9 | chongwu_avatar_4.png |
| 10 | chongwu_avatar_1.png |
| 11 | chongwu_avatar_5.png |
| 12 | chongwu_avatar_1.png |
+----+----------------------+
12 rows in set (0.00 sec)