GROP BY + HAVING 是什么意思啊??
来源:百度知道 编辑:UC知道 时间:2024/06/28 17:53:39
<语法格式>
HAVING condition
§例:
select order_num, avg(total_price)
from items
group by order_num
having count(*) > 2
就是这个 不明白
HAVING condition
§例:
select order_num, avg(total_price)
from items
group by order_num
having count(*) > 2
就是这个 不明白
假定order_num 表示订单号,
group by order_num
having count(*) > 2 表示统一订单上定购物品数目大于2的
打个比方:
订单为:
012000 obj1 obj1
数据库中会保存为:
012000 obj1 price1
012000 obj2 price2
SQL 语言吧,对数据库操作的