1、表A里有个字段aaa,现在我又新建了个字段bbb,我想让对应的每条记录的bbb的值和aaa的值一样,怎么写?2、表C里有个字段ccc,里边的值或者为空,或者是类似/upload/my/......的格式,前边的相同,怎么样把
/upload/my/......的格式修改成/bbs/upload/my/......的格式,为空的字段不修改。
/upload/my/......的格式修改成/bbs/upload/my/......的格式,为空的字段不修改。
UPDATE A SET BBB=AAA
如楼上所述2
update c set ccc=concat('/bbs/',ccc) where ccc is not null;
不成功 ,MYSQL数据库 。。
+------------+
| text |
+------------+
| 1a2b2text |
| |
| 1a2bftext |
| 1a2bastext |
| |
| 1a2b2text |
+------------+
6 rows in set (0.00 sec)mysql> ALTER TABLE `a` ADD `text2` VARCHAR( 50 ) NOT NULL ;
Query OK, 6 rows affected (0.09 sec)
Records: 6 Duplicates: 0 Warnings: 0mysql> select * from a;
+------------+-------+
| text | text2 |
+------------+-------+
| 1a2b2text | |
| | |
| 1a2bftext | |
| 1a2bastext | |
| | |
| 1a2b2text | |
+------------+-------+
6 rows in set (0.00 sec)mysql> update a set text2=text;
Query OK, 4 rows affected (0.00 sec)
Rows matched: 6 Changed: 4 Warnings: 0mysql> select * from a;
+------------+------------+
| text | text2 |
+------------+------------+
| 1a2b2text | 1a2b2text |
| | |
| 1a2bftext | 1a2bftext |
| 1a2bastext | 1a2bastext |
| | |
| 1a2b2text | 1a2b2text |
+------------+------------+
6 rows in set (0.00 sec)
UPDATE A SET BBB=AAA
不成功 ,MYSQL数据库 。。把不成功的提示符贴出来看看?