如何选择按日期分组的 SQL 结果

Question

我想按日期从下表组中选择数据

date        btype       amount
1-2-2017    income      1000
1-2-2017    income      200
1-2-2017    Expense     100
1-2-2017    Expense     200

2-2-2017    income      1000
2-2-2017    income      500
2-2-2017    Expense     1000

3-2-2017    income      2000
3-2-2017    Expense     500

所以我的结果应该是这样的。

date        Income      Expense
1-2-2017    1200        300
2-2-2017    1500        1000
3-2-2017    2000        500

有人会指导我如何编写 SQL 查询来实现这种行为！

Answer 1

这是相当简单的 SQL，您应该能够通过一些 google 弄清楚自己：

select date
      ,sum(if(btype = 'income', amount, 0)) as Income
      ,sum(if(btype = 'expense', amount, 0)) as Expense
from table
group by date

Answer 2

创建测试表后，我插入了一些记录，然后我使用了这个查询：

select date_ as Date_Time, btype, sum(amount) as amount
 from test
 group by date_ , btype

Answer 3

另一种方法

select date
      ,sum(case when btype = 'income' then amount else 0 end) as Income
      ,sum(case when btype = 'expense' then amount else 0 end) as Expense
from table
group by date