select count(*)an2 a inner join product b on a.order_no=b.order_no group by a.plan_id,b.product_no 计算出来的怎么不正确?

Question

多少数据这样能显示出来select a.plan_id as id from plan2 a inner join product b on a.order_no=b.order_no
group by a.plan_id,a.order_no,a.product_no,b.order_no,b.product_no现在怎么计算它有多少条呢？是：select count(*) from plan2 a inner join product b on a.order_no=b.order_no
group by a.plan_id,a.order_no,a.product_no,b.order_no,b.product_no这个好像不对

Answer 1

select count(*) from plan2 a inner join product b on a.order_no=b.order_no
group by a.plan_id,a.order_no,a.product_no

Answer 2

group by a.plan_id,a.order_no,a.product_no,b.order_no,b.product_no
需要用那么多字段用来group by吗？？？
如果只有一个字段group by，如下：
select a.plan_id,count(*) from plan2 a inner join product b on a.order_no=b.order_no
group by a.plan_id

Answer 3

select a.plan_id,count(*) from plan2 a inner join product b on a.order_no=b.order_no
group by a.plan_id
得到的结果是:
total
1
1
2
1
而不是正确答案:4

Answer 4

select sum(1) from plan2 a inner join product b on a.order_no=b.order_no
group by a.plan_id,a.order_no,a.product_no,b.order_no,b.product_no

Answer 5

select a.plan_id,count(*) from plan2 a inner join product b on a.order_no=b.order_no
group by a.plan_id
得到的结果是:
total
1
1
2
1
而不是正确答案:4
你依据a.plan_id来分组了那么还要在select 写上a.plan_id了啊.那不是没有依据任何来分组.看下group 的help

Answer 6

SELECT COUNT(*) AS Expr1FROM plan2 aWHERE (order_no IN          (SELECT DISTINCT order_no         FROM product b         WHERE a.order_no = b.order_no AND a.product_no = b.product_no))

Answer 7

SELECT COUNT(*) AS Expr1FROM plan2 aWHERE (order_no IN          (SELECT DISTINCT order_no         FROM product b         WHERE a.order_no = b.order_no AND a.product_no = b.product_no))

Answer 8

SELECT COUNT(*) AS Expr1FROM plan2 aWHERE (order_no IN          (SELECT DISTINCT order_no         FROM product b         WHERE a.order_no = b.order_no AND a.product_no = b.product_no))