Select Query Joined on Two Fields? - sql

Question

I've got a few tables in an access database:
ID | LocationName
1 | Location1
2 | Location2
ID | LocationID | Date | NumProductsDelivered
1 | 1 | 12/10 | 3
2 | 1 | 01/11 | 2
3 | 1 | 02/11 | 2
4 | 2 | 11/10 | 1
5 | 2 | 12/10 | 1
ID | LocationID | Date | NumEmployees | EmployeeType
1 | 1 | 12/10 | 10 | 1 (=Permanent)
2 | 1 | 12/10 | 3 | 2 (=Temporary)
3 | 1 | 12/10 | 1 | 3 (=Support)
4 | 2 | 10/10 | 1 | 1
5 | 2 | 11/10 | 2 | 1
6 | 2 | 11/10 | 1 | 2
7 | 2 | 11/10 | 1 | 3
8 | 2 | 12/10 | 2 | 1
9 | 2 | 12/10 | 1 | 3
What I want to do is pass in the LocationID as a parameter and get back something like the following table. So, if I pass in 2 as my LocationID, I should get:
Date | NumProductsDelivered | NumPermanentEmployees | NumSupportEmployees
10/10 | | 1 |
11/10 | 1 | 2 | 1
12/10 | 1 | 2 | 1
It seems like this should be a pretty simple query. I really don't even need the first table except as a way to fill in the combo box on the form from which the user chooses which location they want a report for. Unfortunately, everything I've done has resulted in me getting a lot more data than I should be getting. My confusion is in how to set up the join (presumably that's what I'm looking for here) given that I want both the date and locationID to be the same for each row in the result set.
Any help would be much appreciated.
Thanks.
EDIT:
Ok - the answer below didn't quite work, but it did set me on the right track and I was able to use the following query:
SELECT t1.Date, t2.NumProductsDelivered,
(SELECT t1a.NumEmployees
FROM table3 t1a
WHERE t1a.EmployeeType=1 AND t1a.LocationID=t1.LocationID AND t1a.Date= t1.Date)
AS "PermEmps",
(SELECT t1b.NumEmployees
FROM table3 t1b
WHERE t1b.EmployeeType=3 AND t1b.LocationID=t1.LocationID AND t1b.Date=t1.Date)
AS "SupportEmps"
FROM table3 AS t1 LEFT JOIN table2 AS t2 ON (t2.Date=t1.Date)
AND (t2.LocationID=t1.LocationID)
WHERE t1.LocationID=2
GROUP BY t1.Date, t1.LocationID, t2.NumProductsDelivered;
This is getting me the results I was looking for. However, in a case where the location has a break between products being delivered, I don't see the correct results. It seems that the recordset stops as soon as there's an empty row and then never picks back up again. So, where I might expect to see this:
Date | NumProductsDelivered | NumPermanentEmployees | NumSupportEmployees
10/10 | | 1 |
11/10 | 1 | 2 | 1
12/10 | 1 | 2 | 1
01/10 | 2 | | 1
06/10 | 1 | |
I only see this:
Date | NumProductsDelivered | NumPermanentEmployees | NumSupportEmployees
10/10 | | 1 |
11/10 | 1 | 2 | 1
12/10 | 1 | 2 | 1
01/10 | 2 | | 1

Answer 1

I think this would work:
DECLARE #LocationId int
SET #LocationId=2
SELECT L2.LocationId, L2.Date, COUNT(DISTINCT NumProductsDelivered) as NumProductsDelivered,
SUM(case when L2.EmployeeType =1 then NumEmployees else 0 end) as NumPermanentEmployees,
SUM(case when L2.EmployeeType =3 then NumEmployees else 0 end) as NumSupportEmployees
FROM L1
RIGHT JOIN L2
ON L1.LocationID=L2.LocationID
AND L1.Date=L2.Date
WHERE L2.LocationId=#LocationId
GROUP BY L2.LocationId, L2.Date

Answer 2

Something like this should work:
[deleted original]
Try this instead (untested):
select t3.date, t2.numproductsdelivered,
(select sum(t3.numemployees)
from table3 t3a
where t3a.locationid = t3.locationid and t3a.date = t3.date and t3a.employeetype = 1
) as numpermanentemployees,
(select sum(t3.numemployees)
from table3 t3b
where t3b.locationid = t3.locationid and t3b.date = t3.date and t3b.employeetype = 3
) as numsupportemployees
from table3 as t3
left join table2 as t2 on t2.locationid = t3.locationid and t2.date = t3.date
where t3.locationid = 2
group by t3.date, t2.numproductsdelivered
If you didn't mind having separate rows for each employee type it could be simplified:
select t3.date, t2.numproductsdelivered, t3.employeetype, sum(t3.numemployees) as numemployees
from table3 as t3
left join table2 as t2 on t2.locationid = t3.locationid and t2.date = t3.date
where t3.locationid = 2 and t3.employeetype in (1, 3)
group by t3.date, t2.numproductsdelivered, t3.employeetype
Edit: Try this query:
SELECT t1.Date
FROM table3 AS t1
WHERE t1.LocationID=2
GROUP BY t1.Date
...and see if you get all the dates.
Then add the left join:
SELECT t1.Date, t2.NumProductsDelivered
FROM table3 AS t1 LEFT JOIN table2 AS t2 ON (t2.Date=t1.Date)
AND (t2.LocationID=t1.LocationID)
WHERE t1.LocationID=2
GROUP BY t1.Date, t1.LocationID, t2.NumProductsDelivered;
If it's doing a left INNER join, then it will remove rows from t1 that don't have a matching row in t2. Try explicitly setting a left OUTER join and see if that works. The RDBMS I've used the most defaults to outer, but maybe yours (Access) defaults to inner.
So I am thinking the following will work (add "OUTER" and remove "t1.LocationId"):
SELECT t1.Date, t2.NumProductsDelivered,
(SELECT t1a.NumEmployees
FROM table3 t1a
WHERE t1a.EmployeeType=1 AND t1a.LocationID=t1.LocationID AND t1a.Date= t1.Date)
AS "PermEmps",
(SELECT t1b.NumEmployees
FROM table3 t1b
WHERE t1b.EmployeeType=3 AND t1b.LocationID=t1.LocationID AND t1b.Date=t1.Date)
AS "SupportEmps"
FROM table3 AS t1 LEFT OUTER JOIN table2 AS t2 ON (t2.Date=t1.Date)
AND (t2.LocationID=t1.LocationID)
WHERE t1.LocationID=2
GROUP BY t1.Date, t2.NumProductsDelivered;