MySQL: get count value in joins and if else - mysql

Question

In My application I want to display all my friends and no of cheque given and received
Table Transaction Table Friends
---------------------------- -----------------------------
id given_id rev_id amt id who_id whom_id who_name
----------------------------- -------------------------------
1 2 1 1k 1 1 2 sss
2 2 3 1k 2 3 2 fff
3. 3 2 2k 3 4 1 eee
4 1 2 2k 4 2 1 iii
----------------------------- ------------------------------
Result whom_id=2 name=iii -> Friends (sss,fff)
=> sss gives totally 1 cheque and
sss receives totally 1 cheque and
fff gives 1 cheque and
fff receives 1 cheque and
I tried This one..
SELECT
p.who_id,
p.who_name,
COUNT( r1.give_id ) ,
COUNT( r1.rec_id )
FROM
friends p
LEFT JOIN Transaction r1
ON p.who_id = r1.give_id OR p.who_id = r1.rec_id
WHERE
p.whom_id = 1
GROUP BY p.who_id
Please provide me the best way to do this....

Answer 1

You can do it like this
SELECT
f.who_name,
count(t.given_id) GivenTotal,
count(lt.rev_id) as RecievedTotal
from friends as f
left join transaction as t
on t.given_id = f.who_id
left join transaction as lt
on lt.rev_id = f.who_id
where f.whom_id = 2
group by t.given_id
Demo
Output
who_name | GivenTotal | RecievedTotal
----------------------------------
sss | 1 | 1
fff | 1 | 1

Answer 2

try this,
select
id,
count(given_id) as given,
count(rev_id) as reveive
from Friends
GROUP BY id;
and if you whant the difference between the two amounts try this
select
id,
count(given_id) as given,
count(rev_id) as reveive,
given-receive as diff
from Friends
GROUP BY id;

Answer 3

You can use HAVING with group by ,
instead
WHERE p.whom_id = 1

Answer 4

There are two ways to do this, both involve joining on the Transactions table twice.
You can use subqueries:
SELECT f.who_id,
f.who_name,
t1.TotalGiven,
t2.TotalRev
FROM friends f
LEFT JOIN
(
select count(t.given_id) TotalGiven, t.given_id
from Transactions t
group by t.given_id
) t1
ON f.who_id = t1.given_id
LEFT JOIN
(
select count(t.rev_id) TotalRev, t.rev_id
from Transactions t
group by t.rev_id
) t2
ON f.who_id = t2.rev_id
where f.whom_id = 2;
See SQL Fiddle with Demo.
Or you can just use a join with no subquery:
select f.who_id,
f.who_name,
count(t1.given_id) TotalGiven,
count(t2.rev_id) TotalRev
FROM friends f
LEFT JOIN Transactions t1
ON f.who_id = t1.given_id
LEFT JOIN Transactions t2
ON f.who_id = t2.rev_id
where f.whom_id = 2
group by f.who_id, f.who_name
See SQL Fiddle with Demo

Answer 5

Finally I got the answer,
SELECT
p.who_id, p.who_name, COUNT( r1.give_id ) , COUNT( r2.rec_id )
FROM
friends p
LEFT JOIN Transaction r1 ON p.who_id = r1.give_id
LEFT JOIN Transaction r2 on p.who_id = r2.rec_id
WHERE
p.whom_id = 1
GROUP BY p.who_id