1、语法一：SELECT DISTINCT 列名称 FROM 表名称
图中为student表内容
2、查询名叫李四的学生值显示一次
SELECT DISTINCT `name` FROM student
3、根据age排序
SELECT DISTINCT `name` FROM student ORDER BY age
4、根据name,age排序，从左至右优先顺序
SELECT DISTINCT `name` FROM student ORDER BY `name`,age
5、按条件查询name为李四的学生
SELECT `name` FROM student WHERE `name`='李四'
6、加上DISTINCT 去掉重复
SELECT DISTINCT `name` FROM student WHERE `name`='李四'
