Subtract on database value from another 1

[rathcoffey]

I have very limited knowledge of Crystal Reports and have been asked to write a report that shows the open ordered stock quantity sorted by month, purchase order and product code from our ERP package.

I have all the required database fields updating the report correctly. What I am trying to do now is create a field where I can enter the result of quantity ordered minus quantity received. As there are numerous purchase orders and produc codes, there are quite a few of these.

I know this is probably easy, can anyone help?

Thanks

'A world without donuts is like a donut without a hole.......wait that would mean more donut! I'm a Genius' Homer Simpson

 

[Katy44]

You need to use a formula field. You didn't specift your CR version, but hopefully this will work, if you mean to display the difference of two fields:
Go to the field explorer and right click on Formula Fields - choose New, give it a name, and use the editor.
The box at the top left will have all your fields in it - in "Report Fields" if they are on your report already, below if not. The formula is simply the quantity ordered field - the quantity received field. You can use the "x+2" button to check for syntax errors, and then save and close. The field should then appear in the field explorer and you can drag it on to your report.

I hope this has helped, let me know if I have completely misunderstood the question!