IDataParameter.IsNullable IDataParameter.IsNullable IDataParameter.IsNullable IDataParameter.IsNullable Property

定义

获取一个值,该值指示参数是否接受 null 值。Gets a value indicating whether the parameter accepts null values.

public:
 property bool IsNullable { bool get(); };
public bool IsNullable { get; }
member this.IsNullable : bool
Public ReadOnly Property IsNullable As Boolean

属性值

如果接受 null 值,则为 true;否则为 falsetrue if null values are accepted; otherwise, false. 默认值为 falseThe default is false.

示例

下面的示例创建的实现类实例SqlParameter,并设置它的一些属性。The following example creates an instance of the implementing class, SqlParameter, and sets some of its properties.

    private static void AddSqlParameter(SqlCommand command, 
        string paramValue)
    {
        SqlParameter parameter = new SqlParameter(
            "@Description", SqlDbType.VarChar);
        parameter.Value = paramValue;
        parameter.IsNullable = true;
        command.Parameters.Add(parameter);
    }

private static void SetParameterToNull(IDataParameter parameter)
{
    if (parameter.IsNullable)
    {
        parameter.Value = DBNull.Value;
    }
    else
    {
        throw new ArgumentException("Parameter provided is not nullable", "parameter");
    }
}

 Private Sub AddSqlParameter(ByVal command As SqlCommand, _
     ByVal paramValue As String)

     Dim parameter As New SqlParameter( _
         "@Description", SqlDbType.NVarChar, 16)
     parameter.Value = paramValue
     parameter.IsNullable = True
     command.Parameters.Add(parameter)
 End Sub

 Private Shared Sub SetParameterToNull(parameter As IDataParameter)
     If parameter.IsNullable Then
  parameter.Value = DBNull.Value
     Else
         Throw New ArgumentException("Parameter provided is not nullable", "parameter")
     End If
End Sub

注解

处理 null 值使用DBNull类。Null values are handled using the DBNull class.

适用于