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This code provides an IsNull function like that used in SQL Server. This allows you to check if a variable contains null, and if so return a specific value. This can prevent you from having to write things like iif(not isnull(rst!FieldName), rst!FieldName, ""). For new programmers, especially those working with databases, you will quickly become aware that trying to access a database field that contains a null value often results in the dreaded error #94 - Invalid Use of Null, which means you constantly have to write code to trap for that possibility.

Original Author: Jared Scarbrough


ValueToCheck = a variant representing he value to check for null
varWhatToReturnIfNull = the value to return if ValueToCheck is null


If ValueToCheck is null, then varWhatToReturnIfNull is returned, otherwise, ValueToCheck is returned


Public Function IsNullEx(ValueToCheck As Variant, varWhatToReturnIfNull) As Variant
  If IsNull(ValueToCheck) Then
    IsNullEx = varWhatToReturnIfNull
    IsNullEx = ValueToCheck
  End If
End Function
Usage example:
txtClientName = IsNullEx(rst!ClientName, "unknown")

About this post

Posted: 2002-06-01
By: ArchiveBot
Viewed: 143 times


Visual Basic 6


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