sql 基础--mysql 5 （3）

8.计算字段

　　concat () 拼接串

mysql> select concat (name,'-',msg) from pw_luck;
+-----------------------+
| concat (name,'-',msg) |
+-----------------------+
| Wilson-100            |
| zhangsan-100          |
| lisi-1001             |
| wang5-1001            |
| zhangsan7-1000        |
| zhangsan8-1000        |
| zhangsan9-1000        |
| wang5-1000            |
| wang5%-2000           |
| WANG5-1000            |
+-----------------------+
10 rows in set (0.00 sec)

　　RTrim() 去掉右侧空格 LTrim() 去掉左侧空格 Trim() 去掉空格

　　as 别名：

mysql> select concat (name,'-',msg) as temp from pw_luck order by temp;
+----------------+
| temp |
+----------------+
| lisi-1001 |
| wang5%-2000 |
| WANG5-1000 |
| wang5-1000 |
| wang5-1001 |
| Wilson-100 |
| zhangsan-100 |
| zhangsan7-1000 |
| zhangsan8-1000 |
| zhangsan9-1000 |
+----------------+
10 rows in set (0.00 sec)

 算数计算：

mysql> select uid,name,msg, uid+msg as tmp from pw_luck;
+-----+-----------+------+------+
| uid | name      | msg  | tmp  |
+-----+-----------+------+------+
|   0 | Wilson    |  100 |  100 |
|   1 | zhangsan  |  100 |  101 |
|   2 | lisi      | 1001 | 1003 |
|   3 | wang5     | 1001 | 1004 |
|   7 | zhangsan7 | 1000 | 1007 |
|   8 | zhangsan8 | 1000 | 1008 |
|   9 | zhangsan9 | 1000 | 1009 |
|  10 | wang5     | 1000 | 1010 |
|  11 | wang5%    | 2000 | 2011 |
|  12 | WANG5     | 1000 | 1012 |
+-----+-----------+------+------+
10 rows in set (0.03 sec)