How to Use a Custom Method as a User-Defined Function (UDF)

MORE INFORMATION

Custom methods can be coded to behave as functions behave; that is, they can return a value simply by ending the code definition with RETURN x where x is the name of a variable whose value is set in the method.

Custom methods should not begin with the PROCEDURE or FUNCTION command, which is normally used to indicate that a procedure or function is being defined, nor should they end with ENDPROC or ENDFUNC.

Step-by-Step Example

1. Create a new form, and add two text boxes (Text1 and Text2) and two command buttons (Command1 and Command2).
2. Add the Customer and Orders tables from the Testdata database to the data environment of the form.
3. Set the ControlSource for the Text1 box to:

      customer.cust_id
   						

4. Set the ReadOnly property for the Text1 box to True (.T.).
5. Leave the ControlSource property for the Text2 box blank.
6. On the Form menu, click New Method. Enter Custcount as the name of the new method.
7. Change the caption of the Command1 button to "Count orders," and enter the following code in the Click event procedure:

      nNum = thisform.custcount()
      thisform.text2.value = nNum
      thisform.refresh
   						

8. Change the caption of the Command2 button to Skip, and enter the following code in the Click event procedure:

      skip
      thisform.refresh
   						

9. Enter the following code for the Custcount custom method:

      x = 0
      select orders
      go top
      count to x for orders.cust_id = thisform.text1.value
      select customer
      return x
   						

When you click the Count orders button, the Custcount custom method is called to count how many orders exist in the Orders table for the current record in the Customer table. This number is returned to the Count orders button.