Returns a Boolean value that indicates whether an expression evaluates to the System.DBNull class.
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. DBNull is also not the same as a zero-length string (""), which is sometimes referred to as a null string.
This example uses the IsDBNull function to determine if a variable evaluates to DBNull.
Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)