Question

我希望能够在单个mysql查询中选择不同的列。我知道这很容易做到的是sql，但你怎么做的是MySQL？

SELECT
MyfirstResult = (select sum(Counted * PartCost) FROM tblParts WHERE resultofcount < 0),
MySecondresult = (select sum(Counted * PartCost) FROM tblParts WHERE resultofcount > 0)

该查询适用于SQL，但如何将相同的功能移植到MySQl

在这种情况下，我的结果应该是1000 | 2000。一行有2列。

Answer 1

差不多;

SELECT
    (select sum(Counted * PartCost) FROM tblParts WHERE resultofcount < 0) MyfirstResult,
    (select sum(Counted * PartCost) FROM tblParts WHERE resultofcount > 0) MySecondresult;

演示here。

你也可以在MySQL中稍微简单一些;

SELECT sum(Counted * PartCost*(resultofcount < 0)) Myfirstresult,
       sum(Counted * PartCost*(resultofcount > 0)) MysecondResult 
FROM tblParts

演示here。

Answer 2

稍微改变你的语法。列别名遵循计算的表达式或通过AS aliasname进行子选择。

SELECT
  (select sum(Counted * PartCost) FROM tblParts WHERE resultofcount < 0) AS MyFirstResult,
  (select sum(Counted * PartCost) FROM tblParts WHERE resultofcount > 0) AS MySecondResult

mysql使用子查询选择不同结果的列

2 个答案: