mysql入门(五)

   数据处理函数

1：数据表中的记录转化为小写（lower)

select lower(ename) as ename from emp;
+---------+
| ename   |
+---------+
| smith   |
| allen   |
| ward    |
| jones   |
| martim  |
| blake   |
| clark   |
| scoll   |
| king    |
| iusrner |
| adams   |
| james   |
| ford    |
| miller  |
+---------+
14 rows in set (0.13 sec)

2:字段截取（substr)

 select substr(ename,1,3) from emp;
+-------------------+
| substr(ename,1,3) |
+-------------------+
| SMI               |
| ALL               |
| WAR               |
| JON               |
| MAR               |
| BLA               |
| CLA               |
| SCO               |
| KIN               |
| IUS               |
| ADA               |
| JAM               |
| FOR               |
| MIL               |
+-------------------+
14 rows in set (0.00 sec)

mysql> select ename from emp where substr(ename,2,1)='A';
+--------+
| ename  |
+--------+
| WARD   |
| MARTIM |
| JAMES  |
+--------+
3 rows in set (0.01 sec)