SqlDataReader.IsDBNull Method (Int32)

 

Gets a value that indicates whether the column contains non-existent or missing values.

Namespace:   System.Data.SqlClient
Assembly:  System.Data (in System.Data.dll)

Public Overrides Function IsDBNull (
	i As Integer
) As Boolean

Parameters

i
Type: System.Int32

The zero-based column ordinal.

Return Value

Type: System.Boolean

true if the specified column value is equivalent to DBNull; otherwise false.

Call this method to check for null column values before calling the typed get methods (for example, GetByte, GetChar, and so on) to avoid raising an error.

Imports System
Imports System.Data
Imports System.Data.SqlClient

Module Module1
   Sub Main()
      Using connection As New SqlConnection("Data Source=(local);Initial Catalog=AdventureWorks2012;Integrated Security=SSPI")
         Dim command As New SqlCommand("SELECT p.FirstName, p.MiddleName, p.LastName FROM HumanResources.Employee AS e" & _
                                       " JOIN Person.Person AS p ON e.BusinessEntityID = p.BusinessEntityID;", connection)
         connection.Open()
         Dim reader As SqlDataReader = command.ExecuteReader()
         While reader.Read()
            Console.Write(reader.GetString(reader.GetOrdinal("FirstName")))

            ' display middle name only of not null
            If Not reader.IsDBNull(reader.GetOrdinal("MiddleName")) Then
               Console.Write(" {0}", reader.GetString(reader.GetOrdinal("MiddleName")))
            End If

            Console.WriteLine(" {0}", reader.GetString(reader.GetOrdinal("LastName")))
         End While
         connection.Close()
      End Using
   End Sub
End Module

.NET Framework
Available since 1.1
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