Join MySql Tables and SUM - php

Question

I'm trying to write JOIN Query with 3 Tables. I need Query to Return Total SUM of each users based Link Value Passed to Query. Added below the Table Structure, required result and Query that i tried.
Table 1: UserDetails
| ID | Name | Link |
| 1 | User A | 12 |
| 2 | User B | 12 |
| 3 | User C | 12 |
Table 2: Saving
|CreatedBy| Amount |
| 3 | 100 |
| 3 | 50 |
| 2 | 75 |
Table 3: Expense
|CreatedBy| Amount |
| 2 | 20 |
| 1 | 15 |
| 3 | 85 |
By Passing Link Value to Query must return Total(savings+expense) for each user.
Result 1: If Passing Link Value 12.
Query Result be
|User Name| Total |
|User A | 15 |
|User C | 235 |
Result 2: If Passing Link Value 11.
Query Result be
|User Name| Total |
|User B | 95 |
Below query Not returning any result.
SELECT
t1.name,
SUM(t2.total_amount+t3.total_amount)
FROM
userdetails t1
LEFT JOIN savings t2
ON t2.created_by=t1.id
LEFT JOIN expense t3
ON t3.created_by=t1.id
WHERE
t1.link=12
AND t1.status=1
AND t2.status=2
AND t3.status=2
GROUP BY
t2.created_by,
t3.created_by

Answer 1

When you make an outer join you cannot place conditions in the where clause otherwise it nullifies the outer join and turns it into a normal inner join. You can however get what you want (based on your where clause) by adding the condition into the join like this:
SELECT
t1.name,
SUM(t2.total_amount+t3.total_amount)
FROM
userdetails t1
LEFT JOIN savings t2
ON t2.created_by=t1.id
AND t2.status=2
LEFT JOIN expense t3
ON t3.created_by=t1.id
AND t3.status=2
WHERE
t1.link=12
AND t1.status=1
GROUP BY
t2.created_by,
t3.created_by
You also don't normally want to group by fields you aren't naming in your select clause:
SELECT
t1.name,
SUM(t2.total_amount+t3.total_amount)
FROM
userdetails t1
LEFT JOIN savings t2
ON t2.created_by=t1.id
AND t2.status=2
LEFT JOIN expense t3
ON t3.created_by=t1.id
AND t3.status=2
WHERE
t1.link=12
AND t1.status=1
GROUP BY
t1.name

Answer 2

select
u.Name,
u.link,
c.total
from user_details u,
(select
"created by",
sum(amount) Total
from
(select
"created by",
amount
from expense
union all
select
"created by",
amount
from savings)
group by "created by") c
where u.ID=c."created by"
and u.link=12;

Answer 3

Try this:
SELECT A.Name,A.link,B.total
FROM user_details A,
(SELECT 'created by', SUM(amount) AS Total
FROM
(SELECT 'created by',amount
FROM expense
UNION ALL
SELECT'created by',amount
FROM savings)
GROUP BY 'created by') B
WHERE A.ID=B.'created by'
AND A.link=12;
You can use field_name as 'Field Name' or 'Column Title' to display it in the results.
Make sure you have a column created by in the table.