Mysql中的字符串函数

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	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

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