Question

表：orderproducts

orderid   quantity       weight
-----------------------------------
4           5             0.1
4           2             0.5
5           3             2.5
5           7             0.9

1）使用以下SQL命令，可以正确计算总权重，但产品数量是忽略的。如何扩展SQL命令以查询产品数量？

select orderid, sum (weight) as totalweight from orderproducts group by orderid

现在我有了ORDERID 4的值（总重量）=＆gt; 0.6

必须正确=＆gt; 1.5

2）另外，我希望SQL命令“WHERE”（其中other_table.status =“finish”）从另一个表扩展。它也行不通。： - （

select orderid, sum (weight) as totalweight from orderproducts where other_table.status = "finish" group by orderid

Answer 1

查询：

SELECT orderid,
       SUM(weight*quantity) AS totalweight
FROM orderproducts AS a
JOIN othertable AS b ON (b.orderid=b=id)
WHERE b.status = "finish"
GROUP BY orderid

Answer 2

你可以试试这个：

1）产品数量：

select orderid,sum (amount) as totalamount, sum (weight) as totalweight 
   from orderproducts group by orderid

2）除非在其中放置子查询，否则不能将其他表放入当前查询中表的where子句中。试试这个：

select orderid, sum (weight) as totalweight from orderproducts where orderid in 
   (select orderid from other_table where other_table .status = "finish")
group by orderid

Answer 3

1）

select orderid,sum (amount) as totalamount, sum (weight) as totalweight from orderproducts group by orderid

2）你必须使用加入

  select orderid, sum (weight*quantity) as totalweight from orderproducts as a join othertable AS b on (b.orderid=b=id) where b.status = "finish" group by orderid

SQL命令从Amount和ID，总权重计算

3 个答案: