ACC: How to Use the IIf() (Immediate If) Function

MORE INFORMATION

The following example demonstrates how the use of double quotation marks in the IIf() function's arguments can affect the results:

1. Open the sample database Northwind.mdb (or NWIND.MDB in version 1.x or 2.0)
2. Create the following new query based on the Orders table:
   

         Query: Test
         ---------------------------------------
         Field Name: Sum(IIf("[Freight]>50",1,0))
   						

3. Run the query. The result will be the total number of records in the table, not the number of records with Freight charges greater than 50.
4. View the query in Design view. Remove the double quotation marks so the query matches the following:
   

         Query: Test
         -------------------------------------
         Field Name: Sum(IIf([Freight]>50,1,0))
   						

5. Run the query again. The result will be the correct number of records where the freight charge amount is greater than 50.

The double quotation marks around the "[Freight] > 50" argument cause Microsoft Access to evaluate the expression as a string instead of as a comparison. A string will always evaluate to true, while a comparison will test for the condition to be met before returning a value.