Information.IsDBNull(Object) Information.IsDBNull(Object) Information.IsDBNull(Object) Information.IsDBNull(Object) Method

Definition

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

public:
 static bool IsDBNull(System::Object ^ Expression);
public static bool IsDBNull (object Expression);
static member IsDBNull : obj -> bool
Public Function IsDBNull (Expression As Object) As Boolean

Parameters

Expression
Object Object Object Object

Required. Object expression.

Returns

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

Examples

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

Dim testVar As Object
Dim nullCheck As Boolean
nullCheck = IsDBNull(testVar)
testVar = ""
nullCheck = IsDBNull(testVar)
testVar = System.DBNull.Value
nullCheck = IsDBNull(testVar)
' The first two calls to IsDBNull return False; the third returns True.

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. DBNull is also not the same as a zero-length string (""), which is sometimes referred to as a null string.

Applies to

See also