Calculation in Form & Query

[Mohammad Nowfal]

I am working on a Sales Data page of a Rent a car database where I encounter the below problem:

I have the below fields in a FORM (called Sales ) namely:
1. Odometer_Start
2. Odometer_End
3. Kilometer_Driven
4. Extra_Kilometer
5. Total_Days
6. Extra_Kilometer_Charge

and a fied in a SUBFORM (called Car_Data) namely:
1. Kilometer_Allowance (150 per day)

If a customer rent a car at 1000KM and returned it at 1100KM, he drove 100KM though he has 150 allowance. Here in the Extra_Kilometer field I don't want to appeare the negative value (-50), instead, it should be Zero value. Please help me to provide a code in Access.

[mlcampeau]

I am working on a Sales Data page of a Rent a car database where I encounter the below problem:

I have the below fields in a FORM (called Sales ) namely:
1. Odometer_Start
2. Odometer_End
3. Kilometer_Driven
4. Extra_Kilometer
5. Total_Days
6. Extra_Kilometer_Charge

and a fied in a SUBFORM (called Car_Data) namely:
1. Kilometer_Allowance (150 per day)

If a customer rent a car at 1000KM and returned it at 1100KM, he drove 100KM though he has 150 allowance. Here in the Extra_Kilometer field I don't want to appeare the negative value (-50), instead, it should be Zero value. Please help me to provide a code in Access.

You could write an iif statement in a textbox. Something like this:
=iif(([Odometer_End]-[Odometer_Start])<=[Kilometer_Allowance], 0, ([Odometer_End]-[Odometer_Start]-[Kilometer_Allowance]))
I'm not sure if this value is showing up on your main form or subform, but if it is on your main form, you will have to reference Kilometer_Allowance by referring to the subform and vice versa