I am very much a newbie as far as CR goes.  I am trying to produce a report to show stock variances on fuel tanks and I need help with following:

I have:
    DipTanks.Tank : String[50]
    DipTanks.DipDate : DateTime
    DipTanks.DipAmount : Number
    DipTanks.UniqueID : Number

    FuelPurchasesAllocation.TDate : DateTime
    FuelPurchasesAllocation.Tank : String[50]
    FuelPurchasesAllocation.Allocated : Number

    POSTransactionHistory.TDate : DateTime
    POSTransactionHistory.Type : String[2]
    POSTransactionHistory.Tank : String[50]
    POSTransactionHistory.Quantity : Number

My report needs to look something like this:

DipTanks.Tank e.g. "Tank01"
DATE.  OPENING DIP.  PURCHASES.  SALES.    THEORETICAL CLOSING DIP.
  (a)             (b)                  (c)             (d)                         (e)
ACTUAL CLOSING DIP.
                (f)

(a) = Date({DipTanks.DipDate})
(b) = DipTanks.DipAmount
(c) = FuelPurchasesAllocation.Allocated WHERE FuelPurchasesAllocation.Tank = DipTanks.Tank AND Date({FuelPurchasesAllocation.TDate}) = Date({DipTanks.DipDate})
(d) = SUM(POSTransactionHistory.Quantity) WHERE POSTransactionHistory.Tank = DipTanks.Tank AND
POSTransactionHistory.TDate BETWEEN DipTanks.DipDate AND DipTanks.DipDate [Next day]
(e) = (b)+(c)-(d)
(f) = OPENING DIP for the next record.

How can I join Diptanks.Dipdate and FuelPurchasesAllocation.TDate based on the Date element only, or should I use a subreport?

How can I select the sum of the Quantity from the DipDate to the next Dipdate (following day)?

Also the Actual Closing Dip is the Opening Dip for the next day, how do I extract that?

Hope that makes sense and that someone can give me some pointers in the right direction.

Thank you for the response, however I am still not clear on the linking of the tables DipTanks and FuelPurchasesAllocation.  Maybe I should clarify.  Yes there are multiple tanks (5).  Dips of the tanks are taken each day at about 06:30 and the date + time are recorded in DipTanks.DipDate.  Purchases are made on some days but not every day.  The date + time of purchase are recorded in FuelPurchasesAllocation.TDate. The time element of TDate will not match the time element of DipDate, hence my question about linking.

The following example should help:

TABLE : DipTanks
Tank         DipDate                      DipAmount    UniqueID
Tank01    15/12/2011 06:30:20    1,000        201    
Tank02    15/12/2011 06:30:20    5,000        202
Tank01    16/12/2011 06:30:00    6,000        203    
Tank02    16/12/2011 06:30:00    3,000        204
Tank01    17/12/2011 06:30:15    500           205    
Tank02    17/12/2011 06:30:15    9,000        206
Tank01    18/12/2011 06:30:00    7,500        207    
Tank02    18/12/2011 06:30:00    5,000        208

TABLE : FuelPurchasesAllocation
TDate            Tank    Allocated
15/12/2011 10:15:00    Tank01    8,000
15/12/2011 10:15:00    Tank02    4,000
17/12/2011 13:20:00    Tank01    7,500
17/12/2011 13:20:00    Tank02    9,000

From the above tables I require the following partial sample report:


Tank01
DATE        DIP    PURCHASES
15/12/2011    1,000    8,000
16/12/2011    6,000    0
17/12/2011       500    7,500
18/12/2011    7,500    0

As I said, I am very much a newbie at this and I am confused as to whether I should link the tables, but if I do, how do I link on the date element only of DipDate and TDate? Or do I use a subreport, but then how do I reflect zero for the days when there are no purchases?  

Thanks, you have given me some ideas to think about and work on.