Help with Query

Thanks in advance for your help!!!!

I have equipment that I need to track performace after scheduled maintenance (PM) is completed. The information is entered by Equipment number for line and shift. There is a column that contians a numeric value for when a PM is completed (0 = no pm, 1 = pm). All PM is completed on 1st shift. I need to get performance for second shift when a PM is completed on first shift. For example.

Select Production/Potential as Performace, LineNum, Shift, EntryDate
Form tblDailyProduction
Where Shift = 2 AND [a PM has occured on 1st shift]
Group by LineNum, Shift, EntryDate

I just haven't been able to pull out shift 2 on the days that PM is = 1.

I tried to use
Select Production/Potential as Performace, LineNum, Shift, EntryDate
Form tblDailyProduction
Where EntryDate = (Select EntryDate From tblDailyProduction Where PM = 1)
but this did not work as the subquery returned multiple records error.

Here are the table columns:

Name Type
ProdID int
EntryDate Date/Time
LineNum int
Shift int
Dept Text
EquipType Text
ProductType Text
Potential Number (Long)
Production Number (Long)
PM Int
DateCode Text

Thanks,
LeeSelect tDP1.Production/tDP1.Potential as Performace
, tDP1.LineNum
, tDP1.Shift
, tDP1.EntryDate
Form tblDailyProduction tDP1
join tblDailyProduction tDP1 on tDP1.ProdID = tDP2.ProdID
and tDP1.LineNum = tDP2.LineNum
and tDP1.EntryDate = tDP2.EntryDate
Where tDP1.Shift = 2
and tDP2.Shift = 1
and tDP2.PM = 1

my assumptions are:
ProdID = EquipmentID
EntryDate does NOT have a time component.

post back if this is not true|||Yes, EntryDate does not have a time component.
No, ProdID is not the same as equipment number. It is an id for the record. LineNum is the identifier for each piece of equipment. Do I need to set LineNum = LineNum instead of ProdID = ProdID?

Thanks so much for the quick response,
Lee|||caught another mistake...

Select tDP1.Production/tDP1.Potential as Performace
, tDP1.LineNum
, tDP1.Shift
, tDP1.EntryDate
Form tblDailyProduction tDP1
join tblDailyProduction tDP2 on tDP1.LineNum = tDP2.LineNum
and tDP1.EntryDate = tDP2.EntryDate
Where tDP1.Shift = 2
and tDP2.Shift = 1
and tDP2.PM = 1

clear as mud?|||Yes, I made the change and it gave the results (once I change Form to From).

Now that you solved this problem, could I bother you to tell me exactly what is happening so that I can take this "knowledge" that you have so kindly shared and use it in other times of opportunity?

thanks again!!!!!!!!!!!!!
Lee|||Ah, set theory, it's wonderful stuff...

tDP1 gives you a list of all equipment that was used on shift 2.
tDP2 gives you a list of all equipment that had maintenance pulled on the first shift.

Take the intersection of the two lists, via Equipment ID and activity date, to get your answer.

Now don't ask me why I can't spell "FROM" but remember this kind of stuff after being out of school for 20 years!|||THANKS FOR THE POWER!!!