mysql学习记录（六）数据查询

拼搏现实的明天。 2023-06-16 02:22 55阅读 0赞

### mysql学习记录（六）数据查询 ###

*   *   *  select语句的完整句法
         *  查询所有数据
         *  distinct查询
         *  in查询
         *  between and 查询
         *  link模糊查询

### 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;

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTQ2NjUw_size_16_color_FFFFFF_t_70]

### distinct查询 ###

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

![在这里插入图片描述][20191123204645339.jpg]

### 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

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTQ2NjUw_size_16_color_FFFFFF_t_70 1]

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[20191123204645339.jpg]: https://img-blog.csdnimg.cn/20191123204645339.jpg
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