MySQL-查询条件

group by
查询结果分组
[GROUP BY {col_name|position} [ASC|DESC],...]
SELECT class from tb1 GROUP BY class;
having
分组条件
[HAVING where_condiion]
SELECT age from tb1 GROUP BY age HAVING age>10;
order by
对查询结果进行排序
[ORDER BY {col_name|expr|position} [ASC|DESC],...]
limit
限制查询结果返回的数量
[LIMIT {[offset,]row_count|row_count OFFSET offset}]