MYSQL必知必会读书笔记第八章之使用通配符进行过滤_MySQL
mysql简介
MySQL是一种开放源代码的关系型数据库管理系统（RDBMS），MySQL数据库系统使用最常用的数据库管理语言--结构化查询语言（SQL）进行数据库管理。
使用通配符的技巧：
1.不要过度使用通配符。如果其他操作符能达到通配符相同的效果，应该优先的使用其他操作符
2.在确实需要使用通配符时，除非绝对有必要，否则不要把它们用在搜索模式的开始处。把通配符置于搜索模式的开始处，搜索起来是最慢的。
3.仔细注意通配符的位置，如果放错了地方，可能不会返回想要的结果
注意事项:
区分大小写：根据MySQL的配置方式，搜索可以是区分大小写的。如果区分大小写则'jet%'与JetPack 1000将不匹配。
注意尾空格 ：尾空格可能干扰通配符匹配
注意NULL 虽然似乎%可以匹配任何东西，但有一个例外，即NULL。即使是 where prod_name LIKE '%‘ 也不能匹配用值NULL作为产品名的行。
使用的通配符有%匹配的是0个或多个字符。而_只能匹配一个字符。
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