如何从两个表（如一个表的所有行）以及相对于其他表的第一个表的主键总和中获取数据

Question

Table 1:

Table 2:

Result table:

I am in the need of efficient result as my original table one have 100 columns so I need to use aysteric (*). I'm currently working in mysql .

Answer 1

Use an aggregation query:

SELECT
    t1.id,
    t1.Name,
    t1.Email,
    t1.Address,
    t1.Designation
    COALESECE(t2.expenses, 0) AS Expense
FROM Table1 t1
LEFT JOIN
(
    SELECT user_id, SUM(Expense) AS expenses
    FROM Table2
    GROUP BY user_id
) t2
    ON t1.id = t2.user_id;

We could also write the above without a subquery, using a direct join with aggregation. But, with so many columns having appear in the GROUP BY clause, I prefer the version I gave.

Answer 2

You can directly join sum of expense table of each user by using below query.

SELECT userdata.*, (select sum(expense) from expense where expense.user_id=userdata.id) as expense FROM `userdata`  

Or by using left join

SELECT u.*, sum(e.expense) as expense FROM `userdata` u left join expense e on e.user_id=u.id group by u.id 

Here is the full Example of above query (NOTE - PLEASE CHANGE COLUMN NAME ACCORDING TO YOUR TABLE STRUCTURE) .

User table

Expense Table

Then run the query

SELECT userdata.*, (select sum(expense) from expense where expense.user_id=userdata.id) as expense FROM `userdata` 

Response