SQL - Multiple Table Joins - sql

Question

Hi maybe someone can help me here ...
I have a slight problem with an SQL Statement. ( On MS - SQL Server 2008)
So i have 6 Tables looking like this
ID / Company / Month / ClosedTimeStamp / Different Information
Now i need (preferrable in one Statement :P) the count of Datasets from each table grouped by Company and Month at the time it looks something like this.
And there is another thing not all tables need to have data for that Company and that Month so there can be 0 as Result for count(*)
SELECT COUNT(*) as c, Month, Company
FROM Table1 WHERE ClosedTimeStamp IS NULL
GROUP BY Company, Month
ORDER BY Company
I can do this for all the tables and just pick out the results for each company ... Well if someone has any Idea i really would appreciate it :)
Sorry forgot something ... the result should look like this:
Company / Month / CountTable1 / CountTable2 / CountTable3 / .....
Test 02 1 0 50
If it's not possible in one statement well then i have to make it work another way. :)
Thanks
Lim

Answer 1

UNION ALL table rows and then do the count
SELECT COUNT(*) as c, Month, Company
FROM
(
SELECT Month,Company FROM Table1 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company FROM Table2 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company FROM Table3 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company FROM Table4 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company FROM Table5 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company FROM Table6 WHERE ClosedTimeStamp IS NULL
) AS t
GROUP BY Company, Month
ORDER BY Company
If you want the total for each table,company in one row
SELECT SUM(t1) t1,SUM(t2) t2,SUM(t3) t3,SUM(t4) t4,SUM(t5) t5,SUM(t6) t6, Month, Company
FROM
(
SELECT Month,Company, 1 t1,0 t2, 0 t3, 0 t4, 0 t5, 0 t6 FROM Table1 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company, 0 t1,1 t2, 0 t3, 0 t4, 0 t5, 0 t6 FROM Table2 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company, 0 t1,0 t2, 1 t3, 0 t4, 0 t5, 0 t6 FROM Table3 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company, 0 t1,0 t2, 0 t3, 1 t4, 0 t5, 0 t6 FROM Table4 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company, 0 t1,0 t2, 0 t3, 0 t4, 1 t5, 0 t6 FROM Table5 WHERE ClosedTimeStamp IS NULL
UNION ALL
SELECT Month,Company, 0 t1,0 t2, 0 t3, 0 t4, 0 t5, 1 t6 FROM Table6 WHERE ClosedTimeStamp IS NULL
) AS t
GROUP BY Company, Month
ORDER BY Company

Answer 2

If your DB was normalized the query would be much simpler.
Because, your company and Month are spread across 6 tables, we need to make union of those tables in order to get the distinct dataset of all company+month, as such:
select company, month from table1
union
select company, month from table2
union
select company, month from table3
union
select company, month from table4
union
select company, month from table5
union
select company, month from table6
Note, that we need union, not union all, because we don't want the same company+month pair repeated.
Then, just use this dataset to query the quantities for each table:
select t.company, t.month,
(select count(*) from table1
where company = t.company
and month = t.month
and ClosedTimeStamp is null) as qt1,
(select count(*) from table2
where company = t.company
and month = t.month
and ClosedTimeStamp is null) as qt2,
(select count(*) from table3
where company = t.company
and month = t.month
and ClosedTimeStamp is null) as qt3,
(select count(*) from table4
where company = t.company
and month = t.month
and ClosedTimeStamp is null) as qt4,
(select count(*) from table5
where company = t.company
and month = t.month
and ClosedTimeStamp is null) as qt5,
(select count(*) from table6
where company = t.company
and month = t.month
and ClosedTimeStamp is null) as qt6
from (
select company, month from table1
union
select company, month from table2
union
select company, month from table3
union
select company, month from table4
union
select company, month from table5
union
select company, month from table6
) t
order by t.company