如何从另一个表的2个不同的表中获取总和

Question

我正在研究费用/预算跟踪系统，并且陷入了某些困境。

我有4张桌子

tblProjects

tblCategory

tblExpenses

tbl收入

  

tblProject与1：1的tblCategory相关，

     

tblExpenses与1：1的tblProject有关，

     

tbl收入与1：1的tblProjects有关

我正在尝试按年份（从tblProjects.proj_sdate列中获得每个类别组的费用和收入之和），以及一列显示损益（费用-收入）。

例如，我想知道什么是总支出，总收入，旅行，体育等方面的损益的价值？

下面是我想要实现的示例；

我尝试使用以下查询，但返回的数据错误：

SELECT category.cat_title as Category,date_format(projects.proj_sdate, '%Y') 
as Year, (select sum(incomes.inc_amount) from incomes where 
incomes.projects_id = projects.proj_id) as Total_Income, 
(select sum(expenses.exp_amount) from expenses where expenses.projects_id = 
projects.proj_id) as Total_Expenses,
(select ifnull(sum(incomes.inc_amount),0) from incomes where 
incomes.projects_id = projects.proj_id) - (select 
ifnull(sum(expenses.exp_amount),0) from expenses where expenses.projects_id 
= projects.proj_id) as PnL from category inner join projects on 
projects.proj_cat = category.cat_id group by category.cat_id

Answer 1

您可以在下面尝试-

SELECT category.cat_title as Category,Proj_title,
date_format(projects.proj_sdate, '%Y') as Year,
sum(expenses.exp_amount)  as total_income
coalesce(sum(incomes.inc_amount),0) - sum(expenses.exp_amount) as pnl
from 
category inner join projects on projects.proj_cat = category.cat_id
inner join expenses on expenses.projects_id = projects.proj_id
inner join incomes on incomes.projects_id = projects.proj_id
group by category.cat_title,Proj_title,date_format(projects.proj_sdate, '%Y')