mysql学习记录（六）数据查询

select语句的完整句法

select <目标表的列名或列表达式序列>
 from<基本表名和（或）视图序列>
 [where<行条件表达式>]
 [group by   <列名序列>
        [having <组条件表达式>]]
 [order by  <列名[asc|desc]>，…] ;//asc升序默认

查询所有数据

select field1,...,fieldn from tablename ;//列出所有字段名
select * from tablename;

distinct查询

select distinct field1,...fieldn from tablename [where...];//去掉重复值

in查询

select distinct field1,...fieldn from tablename where filedm [not] in(value1,..valuen);
//判断值是否在集合

between and 查询

select distinct field1,...fieldn from tablename where between minvalue and maxvalue;
//查询字段满足范围的值

link模糊查询

%：与零个或多个字符组成的字符串匹配
_：与单个字符匹配