IsDBNull Function

IsDBNull Function

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Class

Microsoft.VisualBasic.Information

Syntax

 IsDBNull(   expression   ) 

expression (required; any expression)

Return Value

Boolean

Description

Determines whether expression evaluates to DbNull (that is, is equal to System.DbNull.Value).

Rules at a Glance

• DbNull is not the same as Nothing or an empty string. DbNull is used to denote the fact that a variable contains a missing or nonexistent value, and it is used primarily in the context of database field values.

• Since any expression that contains DbNull evaluates to DbNull , an expression such as:

   If var = DbNull Then 

  will always fail. The only way to test for a DbNull value is to use IsDbNull .

VB.NET/VB 6 Differences

The IsDBNull function is new to VB.NET.