Join three tables and subtract sum of column from a column data - mysql

Question

I have three tables accounts, receivables and receiveds .
My basic table is receivables I want to get the names from the account table and then subtract the sum of received column in receiveds table form the receivable column in receivables table with same ref numbers. i want to ignore if the balance is zero.
accounts
id
name
22
John
23
Kahn
24
Falis
25
Haseni
26
Gent
receivables
id
receivable
Ref
22
70
A1
24
100
A2
26
60
A3
24
15
A4
receiveds
ref
id
received
A1
22
30
A2
24
60
A1
22
40
A3
26
20
A2
24
10
desired results
id
name
ref
receivable
received
balance
total_id_balance
24
Falis
A2
100
70
30
45
26
Gent
A3
60
20
40
40
24
Falis
A4
15
0
15
45
I have tried this code but it's not working for me
SELECT *
FROM receivables AS rvb
LEFT JOIN accounts AS acc
ON rvb.id = acc.id
LEFT JOIN (SELECT SUM(received) as sum_rvd FROM receiveds) AS rvd
ON acc.id = rvd.id where rvb.receivable>rvd.sum_rvd

Answer 1

INNER JOINs filter out NULL values and the HAVING clause removes zero-balance rows.
SELECT
accounts.* ,
ra.receivable,
rd.received,
ra.receivable - rd.received as balance
FROM accounts
INNER JOIN ( SELECT id, SUM(receivable) as receivable FROM receivables GROUP BY id ) ra
ON ra.id = accounts.id
INNER JOIN ( SELECT id, SUM(received) as received FROM receiveds GROUP BY id ) rd
ON rd.id = accounts.id
HAVING balance > 0
UPDATE
With a ref field we just need to add it as another grouping field for subselects, and change second INNER JOIN to LEFT JOIN (actually looks like it was a mistake from the start, coz we missed entries without receiveds that still had positive balance). Also changing received field to a COALESCE to get zeroes instead of NULL's (indicating non existing rows in a receiveds table).
Since you need an overall per-id total_id_balance field, the natural way to grab it - is using window functions. Note, they are supported only for MySQL 8.0+.
So the resulting query looks like this:
SELECT
accounts.* ,
ra.ref,
ra.receivable,
COALESCE(rd.received, 0) as received,
ra.receivable - COALESCE(rd.received, 0) as balance,
SUM( ra.receivable - COALESCE(rd.received, 0) ) OVER ( PARTITION BY id ) as total_id_balance
FROM accounts
INNER JOIN ( SELECT id, SUM(receivable) as receivable, ref FROM receivables GROUP BY id, ref ) ra
ON ra.id = accounts.id
LEFT JOIN ( SELECT id, SUM(received) as received, ref FROM receiveds GROUP BY id, ref ) rd
ON
rd.id = accounts.id
AND
ra.ref = rd.ref
HAVING balance > 0
ORDER BY ref

Answer 2

This work for me -
EDIT-
Add support for non-unique id in receivables
SELECT acc.id ,acc.name, res.receivable, res.received, (res.receivable - res.received) AS balance
FROM accounts AS acc JOIN
(SELECT recv.id, recv.receivable, rec.received
FROM (
SELECT id, SUM(receivable) AS receivable
FROM receivables
GROUP BY id) AS recv JOIN
(SELECT id, SUM(received) AS received
FROM receiveds
GROUP BY id) AS rec ON rec.id = recv.id
WHERE rec.received < recv.receivable) AS res ON res.id = acc.id;

Answer 3

Assuming it is possible to have an id in receivables without a corresponding id in receiveds, the second join needs to be a LEFT JOIN and you need to handle the NULLs in your SELECT list -
SELECT
a.*,
ra.receivable,
IFNULL(rd.received, 0) received,
ra.receivable - IFNULL(rd.received, 0) balance
FROM accounts a
INNER JOIN (
SELECT id, SUM(receivable) receivable
FROM receivables
GROUP BY id
) ra
ON a.id = ra.id
LEFT JOIN (
SELECT id, SUM(received) received
FROM receiveds
GROUP BY id
) rd
ON a.id = rd.id
HAVING balance > 0;
You can (and should) go a step further and remove the first derived table as it is unnecessary overhead -
SELECT
a.*,
SUM(ra.receivable) receivable,
IFNULL(SUM(rd.received), 0) received,
SUM(ra.receivable) - IFNULL(rd.received, 0) balance
FROM accounts a
INNER JOIN receivables ra
ON a.id = ra.id
LEFT JOIN (
SELECT id, SUM(received) received
FROM receiveds
GROUP BY id
) rd
ON a.id = rd.id
GROUP BY id
HAVING balance > 0;
db<>fiddle