连接属性尚未初始化答案

【问题标题】：Connection property has not been initialized连接属性尚未初始化
【发布时间】：2015-02-17 11:42:03
【问题描述】：

我在列表视图中有数据访问者。我的xml是

<ListView x:Name="listVisitor"  ItemsSource="{Binding}" HorizontalAlignment="Left"
          Height="582" Margin="110,65,0,0" VerticalAlignment="Top" Width="924"
          Grid.ColumnSpan="3" />`
<Button Content="Delete Visitor" Name="Delete" Foreground="white"
        HorizontalAlignment="Left" Margin="236,674,0,0" VerticalAlignment="Top"
        Width="310" Height="30" Background="#FF1CA0B7" Grid.Column="1"
        Click="Delete_Click"/>`

我已经连接到数据库并创建代码来删除数据访问者

代码：

private void Delete_Click(object sender, RoutedEventArgs e)`
{
    if (listVisitor.SelectedItems.Count > 0)
    {
        var connectionString = new ConnectionString();
        var conn = new SqlConnection(connectionString.ViMS_LOCAL());

        DataRowView drv = (DataRowView)listVisitor.SelectedItem;
        string visitorno = drv.Row[0].ToString();

        conn.Open();
        SqlCommand cmd = new SqlCommand("Delete FROM dbo.[Visitor.Profile] Where VisitorNo=@VisitorNo");
        SqlDataAdapter sda = new SqlDataAdapter(cmd);

        cmd.Parameters.AddWithValue("@VisitorNo", visitorno);
        cmd.ExecuteNonQuery();
        BindData();

        }
    }

它显示错误ExecuteNonQuery：连接属性尚未初始化。如何解决这个问题

【问题讨论】：

标签： c# wpf

【解决方案1】：

您必须在调用ExectueNonQuery() 之前设置SqlCommand 对象的Connection 属性。例如：

conn.Open()
SqlCommand cmd = new SqlCommand("Delete FROM dbo.[Visitor.Profile] Where VisitorNo=@VisitorNo");
cmd.Parameters.AddWithValue("@VisitorNo", visitorno);
cmd.Connection = conn; // <- Set the connection
cmd.ExecuteNonQuery();

或者你可以在构造函数中传递它：

SqlCommand cmd = new SqlCommand(
                    "Delete FROM dbo.[Visitor.Profile] Where VisitorNo=@VisitorNo", 
                     conn);

【讨论】：