<?php
/*+++++++++++++++++++
燕十八 公益PHP培训
课堂地址:YY频道88354001
学习社区:www.zixue.it
Mysql中的字符串函数
以goods表为例:
+----------+--------+------------------------------+
| goods_id | cat_id | goods_name |
+----------+--------+------------------------------+
| 1 | 4 | KD876 |
| 4 | 8 | 诺基亚N85原装充电器
| 3 | 8 | 诺基亚原装5800耳机 |
| 5 | 11 | 索爱原装M2卡读卡器
| 6 | 11 | 胜创KINGMAX内存卡 |
| 7 | 8 | 诺基亚N85原装立体声耳机HS-82
| 8 | 3 | 飞利浦9@9v |
| 9 | 3 | 诺基亚E66 |
| 10 | 3 | 索爱C702c |
| 11 | 3 | 索爱C702c |
+----------+--------+------------------------------+
1:group_cancat函数
select group_concat(goods_id,cat_id) from goods;
+-----------------------------------+
| group_concat(goods_id,cat_id) |
+-----------------------------------+
| 14,48,38,511,611,78,83,93,103,113 |
+-----------------------------------+
//将goods_id 与cat_id合并起来默认一逗号隔开
2:length与char_length函数
mysql> select goods_name, char_length(goods_name)from goods where goods_id=9;
+------------+-------------------------+
| goods_name | char_length(goods_name) |
+------------+-------------------------+
| 诺基亚E66 | 6 |
+------------+-------------------------+
select goods_name, length(goods_name)from goods where goods_id=9;
+------------+--------------------+
| goods_name | length(goods_name) |
+------------+--------------------+
| 诺基亚E66 | 12 |
+------------+--------------------+
length函数是计算字段的字节长度由于我存的utf-8所以length是12,如果是gbk应该是9个;
而char_length函数时计算字符长度因此char_length是6个长度.
3:reverse函数
+------------+---------------------+-------------------------+
| goods_name | reverse(goods_name) | char_length(goods_name) |
+------------+---------------------+-------------------------+
| 诺基亚E66 | 66E亚基诺 | 6 |
+------------+---------------------+-------------------------+
4:position与locate函数
+------------+----------------------------+
| goods_name | position('E'in goods_name) |
+------------+----------------------------+
| 诺基亚E66 | 4 |
+------------+----------------------------+
上题使计算'E'在诺基亚E66出现的位置,函数的用法:
position('字符' in (字串));
locate('字符' , (字串));
两个函数效果一样.
5:now函数
select now();
+---------------------+
| now() |
+---------------------+
| 2012-11-01 13:48:21 |
+---------------------+
求出当前时间函数
select curdate();
+---------------------+
|curdate() |
+---------------------+
| 2012-11-01 |
+---------------------+
select curtime();
+---------------------+
| curtime() |
+---------------------+
| 13:48:21 |
+---------------------+
结果出来,不用多解释;
6:加密函数 MD5(),sha();
select MD5(111);
+----------------------------------+
| MD5(111) |
+----------------------------------+
| 698d51a19d8a121ce581499d7b701668 |
+----------------------------------+
mysql> select SHA(111);
+------------------------------------------+
| SHA(111) |
+------------------------------------------+
| 6216f8a75fd5bb3d5f22b6f9958cdede3fc086c2 |
+------------------------------------------+
就给数据加密
7:系统调试函数
show tababase;//显示当前选择的数据库
show user;//显示当前用户
8:mysql函数很多知识举出几个常用的函数
++++++++++++++++++++*/