MySQL_DQL_select_as_别名查询

说明

1. 查询时给列取别名，可使用 AS 关键字
2. 也可以使用 AS 关键字给表取别名
3. AS 也可以省略不写
4. 建议列别名用双引号包裹，不要省略（语法层面可以省略）
5. 表别名不可用双引号包裹

   给列取别名

   语法

   SELECT 字段名1 AS 别名, 字段名2 AS 别名... FROM 表名;

   例子

   select id as "编号", user_name as "用户名", age as "年龄" from tb_user;
   

   给表取别名

   语法

   SELECT 字段名1 AS 别名, 字段名2 AS 别名... FROM 表名 AS 表别名;
   

   例子

   select id as "编号", user_name as "用户名", age as "年龄" from tb_user as my_user;