Question

WPF新手。我想编辑文本框中显示的数据库行的值。目前我收到一个错误：“ExecuteNonQuery：Connection属性尚未初始化”。当我删除where子句时，所有行都会更新，而不仅仅是所选项。

private void btnEDIT_Click(object sender, RoutedEventArgs e)
{
    try
    {
        sc.Open();
        cmd = new SqlCommand("Update Rewards set Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'where Name = '" + this.txtName.Text +"'");
        cmd.ExecuteNonQuery();
        MessageBox.Show("Update Successfull");
        sc.Close();
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

Answer 1

您尚未设置SqlCommand的{{3}}属性。所以命令不知道连接的位置。使用SqlCommand中的Connection或将其设置为此

cmd.Connection = sc;

Answer 2

cmd = new SqlCommand("Update Rewards set Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'where Name = '" + this.txtName.Text +"'",sc); // add connection here

您还应该使用参数化查询或存储过程来阻止SQL注入攻击。

 SqlCommand cmd = new SqlCommand("Update Rewards set Name = @name, Cost= @cost where Name = @name ,sc);
 cmd.Parameters.AddWithValue("@name", Convert.ToString(this.txtName.Text)); and so on

Answer 3

我希望这就是你所需要的:)复制粘贴这个。祝你好运，兄弟！ :)如果您有疑问，请问，如果我知道LOL，我会回答：）

  private void btnEDIT_Click(object sender, RoutedEventArgs e)
{
    try
    {
        sc.Open();
        sql = "UPDATE REWARDS SET Name = '" + this.txtName.Text + "', Cost= '" + this.txtCost.Text + "'WHERE Name = '" + this.txtName.Text +"'");
        SqlCommand command = new SqlCommand(sql, con);
        command.ExecuteNonQuery();
        MessageBox.Show("Update Successfull");
        sc.Close();
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

编辑在文本框中显示的数据库行的值

3 个答案: