Question

我想在一个简单的查询中结合两个单独的查询。我怎么能这样做？

查询：

select idProduct, date,price from products where idProduct like 'Prod01'

idProduct             Date         Price
    Pro01           2014-05-29      19.1
    Pro01           2014-05-29      18.8
    Pro01           2014-05-29      18.7
    Pro01           2014-05-29      18.9
    Pro01           2014-05-29      18.7
    Pro01           2014-05-29      18.5

select idProduct, date,price from products where idProduct like 'Prod02'

idProduct          Date         Price
Pro02           2014-05-29      29.1
Pro02           2014-05-29      28.8
Pro02           2014-05-29      28.7
Pro02           2014-05-29      28.9
Pro02           2014-05-29      28.7
Pro02           2014-05-29      28.5

我想要降低产品的价格＆＃39; Prod02＆＃39;在第四栏。

我解释得很好吗？

基本上我需要这样的东西：

idProduct                     Date         Price of 'Prod01'   Price of 'Prod02'
   Pro01 / Pro02           2014-05-29      19.1                 28.1
   Pro01 / Pro02           2014-05-29      18.8                 26.1
   Pro01 / Pro02           2014-05-29      18.7                 24.1
   Pro01 / Pro02           2014-05-29      18.9                 22.1
   Pro01 / Pro02           2014-05-29      18.7                 21.1
   Pro01 / Pro02           2014-05-29      18.5                 22.1

Answer 1

SELECT *
FROM(
SELECT idProduct, Date,(Price) as Price01, '0' as Price02
FROM products
WHERE idProduct LIKE 'Prod01'
UNION
SELECT idProduct, Date,'0' as Price01, (Price) as Price02
FROM products 
WHERE idProduct like 'Prod02'
) as temp

Answer 2

如果日期列中有不同的时间戳，可以使用JOIN来获取数据（每行只包含日期，并且总是相同但不起作用）

SELECT concat(p1.idProduct, ' / ', p2.idProduct) idProduct
     , p1.`Date`
     , p1.`Price` as `Price of Prod01`
     , p2.`Price` as `Price of Prod02`
FROM   (SELECT idProduct, Date, Price
        FROM products
        WHERE idProduct LIKE 'Pro01') p1
       LEFT  JOIN (SELECT idProduct, Date, Price
                   FROM products
                   WHERE idProduct LIKE 'Pro02') p2
       ON p1.Date = p2.Date

SQLFiddle Demo

如果两个产品的行要以相同的顺序（哪个顺序？），你可以使用MySQL版本的Row_Number

SELECT concat(p1.idProduct, ' / ', p2.idProduct) idProduct
     , p1.`Date` `Date of Prod01`
     , p2.`Date` `Date of Prod02`
     , p1.`Price` as `Price of Prod01`
     , p2.`Price` as `Price of Prod02`
FROM   (SELECT idProduct, Date, Price
             , @rownum := @rownum + 1 AS ID
        FROM products,
             (SELECT @rownum := 0) r
        WHERE idProduct LIKE 'Pro01') p1
       LEFT  JOIN (SELECT idProduct, Date, Price
                        , @rownum2 := @rownum2 + 1 AS ID
                   FROM   products,
                          (SELECT @rownum2 := 0) r
                   WHERE idProduct LIKE 'Pro02') p2
       ON p1.ID = p2.ID

SQLFiddle demo

但我真的希望你的时间戳不仅仅是日期。

如何在一个简单的查询中联合两个单独的查询 - MySQL

2 个答案: