如何使用1个mysql语法从3个表中获得2个结果

Question

我有3张这样的表

soft_id   soft_name
1         Office

pu_id   soft_id   pu_quantity
1       1         10
2       1         20
3       1         30

own_id   soft_id   owner
1        1         Peter
2        1         Tommy
3        1         David

如何在一个单独的mysql查询中得到这样的结果

soft_id   soft_name   sum(pu_quantity)   count(owner)
1         Office      60                 3

Answer 1

试试这个

SELECT S.soft_id,S.soft_name,P.sum(pu_quantity),O.count(owner)
FROM Soft S INNER JOIN Product P ON S.soft_id = P.soft_id
Inner JOIN Owner O = P.soft_id = O.soft_id
Group By S.soft_id,P.soft_id,O.soft_id,S.soft_name

Answer 2

试试这个：

SELECT a.soft_id,
  a.soft_name,
  b.p_cnt AS quantity,
  c.o_cnt AS owner_count
FROM soft a
INNER JOIN
  (SELECT soft_id, SUM(pu_quantity) AS p_cnt FROM product GROUP BY soft_id
  ) b
ON a.soft_id = b.soft_id
INNER JOIN
  (SELECT soft_id, COUNT(*) AS o_cnt FROM owner GROUP BY soft_id
  ) c
ON b.soft_id = c.soft_id
GROUP BY a.soft_id,
  a.soft_name

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SQLFiddle

注意：假设表名分别是软，产品和所有者。