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Information.IsDBNull Method

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

Namespace:  Microsoft.VisualBasic
Assembly:  Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)

public static bool IsDBNull(
	Object Expression
)

Parameters

Expression
Type: System.Object

Required. Object expression.

Return Value

Type: System.Boolean
Returns a Boolean value indicating 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.

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.

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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