SqlDataReader.IsDBNull(Int32) Méthode

Définition

Espace de noms:
System.Data.SqlClient
Assembly:
System.Data.SqlClient.dll
Assembly:
System.Data.dll
Source:
System.Data.SqlClient.notsupported.cs

Obtient une valeur qui indique si la colonne contient des valeurs inexistantes ou manquantes.

public:
 override bool IsDBNull(int i);
public:
 virtual bool IsDBNull(int i);
public override bool IsDBNull(int i);
public bool IsDBNull(int i);
override this.IsDBNull : int -> bool
abstract member IsDBNull : int -> bool
override this.IsDBNull : int -> bool
Public Overrides Function IsDBNull (i As Integer) As Boolean
Public Function IsDBNull (i As Integer) As Boolean

Paramètres

i
Int32

Ordinal de colonne de base zéro.

Retours

Boolean

true si la valeur de colonne spécifiée est équivalente à DBNull; sinon false.

Implémente

IsDBNull(Int32)

Remarques

Appelez cette méthode pour vérifier les valeurs de colonne Null avant d’appeler les méthodes get typées (par exemple, GetByte, GetCharet ainsi de suite) pour éviter de déclencher une erreur.

using System;
using System.Data;
using System.Data.SqlClient;

class Program {
   static void Main(string[] args) {

      using (var connection = new SqlConnection(@"Data Source=(local);Initial Catalog=AdventureWorks2012;Integrated Security=SSPI")) {
         var command = 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();
         var reader = command.ExecuteReader();
         while (reader.Read()) {
            Console.Write(reader.GetString(reader.GetOrdinal("FirstName")));
            // display middle name only of not null
            if (!reader.IsDBNull(reader.GetOrdinal("MiddleName")))
               Console.Write(" {0}", reader.GetString(reader.GetOrdinal("MiddleName")));
            Console.WriteLine(" {0}", reader.GetString(reader.GetOrdinal("LastName")));
         }
         connection.Close();
      }
   }
}

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

S’applique à

Voir aussi