MySQL multiple Left Join gets wrong output

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Hello, Im a beginner in MySQL. Im trying to query out some data from a voip calling card database for which I needed to join multiple table. It was giving correct output till there was two left join table, but when I added third table then the "total duration" column is giving wrong output.

My First query looked like this and the output was in this screencap ( http://i.stack.imgur.com/M8JN6.png ):

SQL

select c.login,cname.Name,cname.LastName,DATE_FORMAT(Creation_Date,'%d-%m-%y')as regdate,DATE_FORMAT((Select max(call_start) from calls where calls.id_client = c.id_client),'%d-%m-%y') as lastcall, c.account_state,sum(cdr.duration / 60) as total_duration from clientsshared as c
    left join invoiceclients as cname on cname.IdClient = c.id_client
    left join calls as cdr on cdr.id_client = c.id_client
    where c.id_reseller='10' group by c.id_client order by total_duration desc limit 100

The new query is like this which gives wrong output, please check the screencap ( http://i.stack.imgur.com/usce8.png ):

SQL

select c.login,cname.Name,cname.LastName,DATE_FORMAT(Creation_Date,'%m-%d-%y')as regdate, 
	(Select max(data) from payments where payments.id_client = c.id_client) as lastpayment,
	(Select max(call_start) from calls where calls.id_client = c.id_client) as lastcall, 
	c.account_state,sum(cdr.duration / 60) as total_duration from clientsshared as c

	left join invoiceclients as cname on cname.IdClient = c.id_client
	left join payments as p on p.id_client = c.id_client
	left join calls as cdr on cdr.id_client = c.id_client
	where c.id_reseller='10' group by c.id_client order by total_duration desc limit 100

Posted 3-Aug-15 1:38am

Member 11881930

Updated 3-Aug-15 1:40am

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Richard Deeming · Accepted Answer · 2015-08-03T04:59:00

You're multiplying the total duration for all calls for the client by the total number of payments the client has made.

The query doesn't actually use the left join to the payments table, so you can just remove it:

SQL

select 
    c.login,
    cname.Name,
    cname.LastName,
    DATE_FORMAT(Creation_Date,'%m-%d-%y')as regdate, 
    (Select max(data) from payments where payments.id_client = c.id_client) as lastpayment,
    (Select max(call_start) from calls where calls.id_client = c.id_client) as lastcall, 
    c.account_state,
    sum(cdr.duration / 60) as total_duration 
from 
    clientsshared as c
    left join invoiceclients as cname on cname.IdClient = c.id_client
    left join calls as cdr on cdr.id_client = c.id_client
where 
    c.id_reseller='10' 
group by 
    c.id_client 
order by 
    total_duration desc 
limit 100