Left Outer Join SSMS - sql

Question

I am attempting to left outer join between two tables.
select id, startdate, name, code, email from edw.dbo.starts
id startdate name code email yearfiled
15 2/4/2018 SO 1083 sql#gmail.com 2018
17 3/4/2018 SO 1083 ssms#gmail.com 2018
19 4/4/2018 SO 1083 ssrs#gmail.com 2018
21 5/4/2018 SO 1083 ssas#gmail.com 2018
21 5/5/2017 SO 1083 who#gmail.com 2017
select customer, return_year, revenue, code from sql.dbo.paid
customer return_year revenue code
15 2018 15.00 1083
17 2018 25.00 1083
21 2018 35.00 1083
21 2017 35.00 1083
select
month(os.startdate) as startmonth
,os.name
,os.code
,coalesce(s.revenue, 0) as revenue
,count(os.email) as commission
from
edw.dbo.starts as os
left outer join
sql.dbo.paid as s
on
os.id = s.customer
and os.yearfile = s.return_year
where
os.yearfiled = 2018
and os.code = '1083'
and os.startdate is not null
group by
month(os.startdate)
,os.name
,os.code
,coalesce(s.revenue, 0);
startmonth name code revenue commission
2 SO 1083 15.00 1
3 SO 1083 25.00 1
4 SO 1083 0.00 1
5 SO 1083 0.00 1
The issue:
Customer = 21 from sql.dbo.paid shows zero for the revenue in the joined query even though it had a reported $35.00 revenue in the table.
Requested:
startmonth name code revenue commission
2 SO 1083 15.00 1
3 SO 1083 25.00 1
4 SO 1083 0.00 1
5 SO 1083 35.00 1

Answer 1

Please try this one.
create table starts
(id int ,
startdate date ,
name varchar(10),
code int ,
email varchar(20),
yearfiled int )
create table paid
( customer int ,
return_year int ,
revenue decimal(10,2),
code int)
insert into starts values
(15,'2/4/2018','SO',1083,'sql#gmail.com',2018),
(17,'3/4/2018','SO',1083,'ssms#gmail.com',2018),
(19,'4/4/2018','SO',1083,'ssrs#gmail.com',2018),
(21,'5/4/2018','SO',1083,'ssas#gmail.com',2018),
(21,'5/5/2017','SO',1083,'who#gmail.com',2017)
insert into paid values
(15,2018,15.00,1083),
(17,2018,25.00,1083),
(21,2018,35.00,1083),
(21,2017,35.00,1083)
select month(a.startdate)as startmonth,a.name,a.code,
case when b.revenue is null then 0 else b.revenue end as revenue,
count(a.email) as commission
from starts a
left join paid b on a.yearfiled=b.return_year and a.id=b.customer
where a.yearfiled=2018 and a.code=1083
group by month(a.startdate),a.name,a.code,b.revenue
/*
startmonth name code revenue commission
----------- ---------- ----------- --------------------------------------- -----------
2 SO 1083 15.00 1
3 SO 1083 25.00 1
4 SO 1083 0.00 1
5 SO 1083 35.00 1
*/