Returns a Boolean value indicating whether an expression evaluates to the System.DBNull class.

Public Function IsDBNull(ByVal Expression As Object) As Boolean

Parameter

Expression

Required. Object expression.

Remarks

IsDBNull returns True if the data type of Expression evaluates to the DBNull type; otherwise, IsDBNull returns False.

The System.DBNull value indicates that the Object represents missing or nonexistent data. DBNull is not the same as Nothing, which indicates that a variable has not yet been initialized. It is also not the same as a zero-length string (""), which is sometimes referred to as a null string.

Example

This example uses the IsDBNull function to determine if a variable evaluates to DBNull.

Dim MyVar As Object
Dim MyCheck As Boolean
MyCheck = IsDBNull(MyVar)   ' Returns False.
MyVar = ""
MyCheck = IsDBNull(MyVar)   ' Returns False.
MyVar = System.DBNull.Value
MyCheck = IsDBNull(MyVar)   ' Returns True.
MsgBox(MyCheck)

See Also

IsArray Function | IsDate Function | IsError Function | IsNothing Function | IsNumeric Function | IsReference Function | Object Data Type | DBNull Class | TypeName Function