Here is a common question: “How can I make a field mandatory to my users?”
Well, as always, there are different techniques that can be employed. I will breifly covert 2: using Table Field Properties and using Form Events.
Table Setup
The easiest method is to merely set the table’s Required field property to Yes.
That said, this approach does present limitations. Mainly the fact that the message returned to the user references the Field Name (see the example below) and not its’ Caption or Description or Form Control Name, so the message in fact ends up confusing most users! This is why, using form event can come in handy.
The field ‘YourFieldName’ cannot contain a Null value because the Required property for this field is set to True. Enter a value in this field.
Form Event
Happily, we can add a lot more functionality and user-friendliness to our form by using its’ BeforeUpdate event to perform our validation. By inserting a little VBA code, for instance, something along the lines of:
Private Sub Form_BeforeUpdate(Cancel As Integer) If IsNull(Me.[YourControlName]) Then Cancel = True MsgBox "You must enter a value for 'YourControlNameOrYourDescription'. Please make a valid entry or press ESC to Cancel" 'You could set the focus on the specific control if your wish, change the background color, ... End If End Sub
As you can see, both are easy to implement, but the second method offers much more control and you can explain to your users in plain English to problem. Furthermore, you could also perform more advance data validation to not only ensure they have made an entry, but that it meet the require format…
Tuesday, May 3rd, 2011, 9:34 pm | 
MS Access Forms, MS Access Tables | 
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