Information.IsDBNull Method (Object)

 
System_CAPS_noteNote

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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
Available since 1.1
Silverlight
Available since 2.0
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