从两个日期之间获取数据

Question

我有这两个表

第一个是费用表，第二个是费用名称

Exp_Type（第一个表）是费用名称（第二个表），因为2是Food

我正在尝试根据费用类型对费用进行分组，并在某些日期之间获取数据。

这是我尝试过的，但它无法正常工作。

select
(select 
(select name from EXPENSENAME where id=EXP_TYPE)as ExpenseType,
sum(PRICE) as cost
from EXPENSES WHERE USERID=1  GROUP BY EXPENSES.EXP_TYPE),
[date]
from EXPENSES where [date] BETWEEN '10-09-2015' and '10-18-2015 23:59:59'

And

select 
(select name from EXPENSENAME where id=EXP_TYPE)as ExpenseType,
sum(PRICE) as cost,
date
from EXPENSES WHERE USERID=1 and DATE BETWEEN '01/10/2015' and '29/10/2015' GROUP BY EXPENSES.EXP_TYPE

没有日期，我通过此查询得到结果，但我需要在某些日期之间使用相同的数据，请帮助

select 
(select name from EXPENSENAME where id=EXP_TYPE)as ExpenseType,
sum(PRICE) as cost
from EXPENSES WHERE USERID=1  GROUP BY EXPENSES.EXP_TYPE

Answer 1

你想要一起加入表格

SELECT en.name as ExpenseType, SUM(e.price) as cost
FROM expenses e
JOIN expensename en ON en.id = e.exp_type
WHERE e.date BETWEEN '10-09-2015' and '10-18-2015'
GROUP BY en.name

这应该给你每个名字的费用

你当前的查询是可怕的...这就是为什么

SELECT (SELECT ... FROM ... WHERE ... ) as ...

这是创建一个相关子查询，它对父选择的每一行执行一次。意思是如果你有一个包含4行的表(SELECT ... FROM ... WHERE ... )将执行4次扫描16行（假设它来自同一个表），这通常是一种非常糟糕的获取数据的方法...如果你有一个百万行...好好做数学，这是一个坏主意