SQL: Using one table as a criteria for itself - sql

Question

I am trying to use a parameter of a table as a criteria for itself, and can't quite get my sql statement right. It seems to be a relatively simple query; I'm using a sub query for my criteria, but it is not filtering out other rows on my table.
Background:
Manufacturing production floor: I have a bunch of machinists on their machines right now running an operation (OprSeq) of a job (JobNum). From the LaborDtl table, which keeps a record of all labor activity, I can see what labor is currently active (ActiveTrans = 1). With this criteria of active labor, I want to sum up all the past labor transactions on each active labor entry. So I need a LaborDtl table of inactive labor activity with the criteria of active labor from the same table.
The code:
Heres my 'criteria' subquery:
SELECT
LaborDtl.JobNum,
LaborDtl.OprSeq
FROM Erp.LaborDtl
WHERE LaborDtl.ActiveTrans = 1
Which returns active transactions, here's the first couple (sorted by job):
Job Operation
000193 90
000457 70
000457 70
020008-1 140
020008-2 130
020010 60
020035 130
020175 40
020175-2 50
020186 80
020199 10
020203 50
020212 40
020258 60
020272 10
020283 30
020298 10
020299 30
Then here's the full SQL Statement, with the query above embedded:
SELECT
LaborDtl.JobNum,
LaborDtl.OprSeq as "Op",
SUM(LaborDtl.LaborQty) as "Total Labor"
FROM Erp.LaborDtl
WHERE EXISTS
(
SELECT
LaborDtl.Company,
LaborDtl.JobNum,
LaborDtl.OprSeq
FROM Erp.LaborDtl
WHERE LaborDtl.ActiveTrans = 1 --Labor table of just current activity
)
GROUP BY LaborDtl.JobNum, LaborDtl.OprSeq
I expect to see only the Job and Operation numbers that exist in my sub query, but I'm getting both jobs and operations that don't exist in my sub query. Here are the first 10 (note, the first JobNum should be 000193 per my criteria)
JobNum Op Total Labor
0 0.00000000
000004 1 32.00000000
000019 1 106.00000000
000029 1 175.00000000
000143 1 85.00000000
000164 1 58.00000000
000181 1 500.00000000
000227 1 116.00000000
000421 1 154.00000000
000458 1 67.00000000

Answer 1

You're missing some condition to tie the outer and inner queries together. Right now, without that criteria, the inner query just returns "true", as there are jobs with active activities and thus all the rows in the outer query are returned. Note that you'll have to add aliases to the tables, as the inner and outer query use the same table:
SELECT a.JobNum, a.OprSeq as "Op", SUM(a.LaborQty) as "Total Labor"
FROM Erp.LaborDtl a
WHERE EXISTS (SELECT * -- The select list doesn't really matter here
FROM Erp.LaborDtl b
WHERE a.JobNum = b.JobNum AND -- Here!
a.OprSeq = b.OprSeq AND -- And here!
b.ActiveTrans = 1 -- Labor table of just current activity
)
GROUP BY a.JobNum, a.OprSeq
Note, however, that there's an easier (IMHO) way. Since you're grouping by JobNum and OprSeq anyway, you could just count the number of active transactions and using a having clause to query only those that have at least one active transaction:
SELECT JobNum, OprSeq as "Op", SUM(LaborQty) as "Total Labor"
FROM Erp.LaborDtl
GROUP BY JobNum, OprSeq
HAVING COUNT(CASE ActiveTrans WHEN 1 THEN 1 END) > 0

Answer 2

Without knowing RDBMS vendor and version this is the best I can do:
SELECT
t1.JobNum,
t1.OprSeq as "Op",
SUM(t1.LaborQty) as "Total Labor"
FROM Erp.LaborDtl t1
WHERE EXISTS
(
SELECT 1
FROM Erp.LaborDtl t2
WHERE t2.ActiveTrans = 1 --Labor table of just current activity
and t2.Company = t1.Company
and t2.JobNum = t1.JobNum
and t2.OprSeq = t1.OprSeq
)
GROUP BY t1.JobNum, t1.OprSeq