Question

当用户在页面上的三个框中输入特定值时，我有代码将数据插入表中。

这些方框是订单号，总重量和跟踪参考。

我现在需要为此代码添加更多功能，首先检查订单号是否存在，如果需要更新列，如果不是，我需要插入新行并添加数据这一点。

我在想，就像IF结果= 0，插入NEW，ELSE更新

如何修改我的代码才能执行此操作？

protected void Page_Load(object sender, EventArgs e)
{
    errorLabel.Visible = false;
    successLabel.Visible = false;
    errorPanel.Visible = false;
}

protected void submitBtn_Click(object sender, EventArgs e)
{
    if (Page.IsValid)
    {
        int _orderID = Convert.ToInt32(orderID.Text);
        string _trackingID = trackingNumber.Text;
        DateTime _date = DateTime.UtcNow;
        int _weightID = Convert.ToInt32(weightID.Text);

        SqlConnection myConnection = new SqlConnection("Data Source=localhost\\Sqlexpress;Initial Catalog=databasename;User ID=username;Password=password");
        SqlCommand myCommand = new SqlCommand("INSERT into Shipment (TrackingNumber, OrderId, ShippedDateUtc, CreatedOnUtc, TotalWeight) VALUES (@tracking, @order, @date, @date, @weight)", myConnection);

        try
        {
            myConnection.Open();
            myCommand.Parameters.AddWithValue("@order", _orderID);
            myCommand.Parameters.AddWithValue("@tracking", _trackingID);
            myCommand.Parameters.AddWithValue("@date", _date);
            myCommand.Parameters.AddWithValue("@weight", _weightID);
            int rowsUpdated = myCommand.ExecuteNonQuery();
            myConnection.Close();
            if (rowsUpdated > 0)
            {
                alertdiv.Attributes.Add("class", "alert alert-success form-signin");
                successLabel.Text = "Thank you, tracking details have been updated";
                successLabel.Visible = true;
                errorPanel.Visible = true;

            }
            else
            {

                alertdiv.Attributes.Add("class", "alert alert-error form-signin");
                errorLabel.Text = "Oh dear, the order number is not recognised, please check and try again";
                errorLabel.Visible = true;
                errorPanel.Visible = true;
            }

            orderID.Text = "";
            trackingNumber.Text = "";
            weightID.Text = "";
        }
        catch (Exception f)
        {
            errorLabel.Text = "This order number does not exist, please check";
            errorLabel.Visible = true;
            errorPanel.Visible = true;
            return;

        }
    }
}

protected void Signout_Click(object sender, EventArgs e)
{
    FormsAuthentication.SignOut();
    Response.Redirect("Login.aspx");
}

Answer 1

您可以在SELECT声明之前添加一些INSERT查询。因此，如果SELECT查询返回多行，则表示您已在数据库中拥有该记录，并且需要更新。所以，一般情况下它会像

SqlCommand cmdCount = new SqlCommand("SELECT count(*) from Shipment WHERE OrderId = @order", myConnection);
cmdCount.Parameters.AddWithValue("@order", _orderID);
int count = (int)cmdCount.ExecuteScalar();

if (count > 0)
{
     // UPDATE STATEMENT
     SqlCommand updCommand = new SqlCommand("UPDATE Shipment SET TrackingNumber = @tracking, ShippedDateUtc = @date, TotalWeight = @weight", myConnection);
     updCommand.Parameters.AddWithValue("@order", _orderID);
     updCommand.Parameters.AddWithValue("@tracking", _trackingID);
     updCommand.Parameters.AddWithValue("@date", _date);
     updCommand.Parameters.AddWithValue("@weight", _weightID);
     int rowsUpdated = myCommand.ExecuteNonQuery();
}
else
{
     // INSERT STATEMENT
     SqlCommand insCommand = new SqlCommand("INSERT into Shipment (TrackingNumber, OrderId, ShippedDateUtc, CreatedOnUtc, TotalWeight) VALUES (@tracking, @order, @date, @date, @weight)", myConnection);
     insCommand.Parameters.AddWithValue("@order", _orderID);
     insCommand.Parameters.AddWithValue("@tracking", _trackingID);
     insCommand.Parameters.AddWithValue("@date", _date);
     insCommand.Parameters.AddWithValue("@weight", _weightID);
     int rowsUpdated = myCommand.ExecuteNonQuery();
}

修改或者更短：

SqlCommand command; if (count > 0) { command = new SqlCommand("UPDATE Shipment SET TrackingNumber = @tracking, ShippedDateUtc = @date, TotalWeight = @weight WHERE OrderId = @order", myConnection); } else { command = new SqlCommand("INSERT into Shipment (TrackingNumber, OrderId, ShippedDateUtc, CreatedOnUtc, TotalWeight) VALUES (@tracking, @order, @date, @date, @weight)", myConnection); } command.Parameters.AddWithValue("@order", _orderID); command.Parameters.AddWithValue("@tracking", _trackingID); command.Parameters.AddWithValue("@date", _date); command.Parameters.AddWithValue("@weight", _weightID); int rowsUpdated = command.ExecuteNonQuery();

Answer 2

最有效的方法是将功能放入存储过程，例如（伪代码）： IF EXISTS(SELECT * FROM Orders WHERE OrderNo = @orderNo) UPDATE ...

ELSE INSERT ...

如果无法创建新的存储过程，也可以创建包含此Statement的命令，但可读性通常更差。
这两种方法只需要一个DB请求。

c＃update如果存在记录，则插入新记录

2 个答案: