Question

假设我有下表记录谁投资了公司名单。

Table: corporate_investments

company investor investment date
--------------------------------
CorpA    Alice     10       12/1
CorpB    Bob       20       12/2
CorpB    Sally     20       12/3 
CorpC    Cathy     30       12/4
CorpC    Alice     40       12/5
CorpC    Bob       10       12/6
CorpC    Bob       20       12/7

我如何运行返回每家公司的查询，Bob（谁是VIP）的总投资以及该公司的总投资？

我试过了

SELECT company,SUM(investment) as total investment
FROM corporate_investments
GROUP BY company

成功找到投入的总金额。

company    total_investment
---------------------------
CorpA           10
CorpB           40
CorpC          100

现在我想为每家公司添加Bob的总金额。我需要像SUM（）函数本身的一个子句，但我很困惑如何做到这一点。

Answer 1

使用条件聚合：

SELECT company, SUM(investment) as total,
       sum(case when investor = 'Bob' then investment else 0 end) as BobTotal
FROM corporate_investments
GROUP BY company;

Answer 2

您可以使用WITH ROLLUP获得每位投资者的总计：

SELECT company, investor, SUM(investment) AS total
FROM corporate_investments
GROUP BY company, investor WITH ROLLUP

哪会产生这样的结果：

CorpA    Alice     10
CorpA    NULL      10
CorpB    Bob       20
CorpB    Sally     20
CorpB    NULL      40
CorpC    Alice     40
CorpC    Bob       30
CorpC    Cathy     30
CorpC    NULL     100

SQL：如何在两个不同的条件上使用相同的值

2 个答案: