Information.IsDBNull(Object) Method
Definition
Important
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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);
public static bool IsDBNull (object Expression);
static member IsDBNull : obj -> bool
Public Function IsDBNull (Expression As Object) As Boolean
Parameters
- Expression
- 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
.NET
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