如何增加列和更新数据库的价值 [英] How To Add Value To A Column And Update Database

问题描述

我正在尝试将 dataGridViewAFp1 中的列 Annual_Fees 的值添加到新的值 AF2 文本框 txtp1AF.Text 我确实转换为整数。然后，将 ResultAF 的结果转换回到 updatedAF ，这是数据库中要更新的值。我将变量 AF11 初始化为0.查询确实更新了所选列。这个想法是获取 AF2 中的任何值，并将其添加到特定于该栏中的任何值，我在数据库中放入 AF11 strong>因此更新的值 updatedAF 。这是我迄今为止所做的，但似乎没有工作。这些值不是相加的。

I am trying to add the value of the column Annual_Fees in dataGridViewAFp1 to a new value AF2 from the textbox txtp1AF.Text that I did convert to integer. Then the result from the addition ResultAF is converted back to string updatedAF and that's the value to be updated in the database. I did initialize variable AF11 to 0. The query does update the selected columns. The idea is to get whatever value is in AF2 and add it to whatever value is in that column and row specifically which i put in AF11 in the database hence the updated value updatedAF. Here's what I have done so far but doesn't seem to be working. The values are not adding up.

 private void btnEnterAFp1_Click(object sender, EventArgs e)
    {            
        if (string.IsNullOrWhiteSpace(txtp1AF.Text))
        {                

            MessageBox.Show("Please Enter fee","Oops",MessageBoxButtons.OK,MessageBoxIcon.Warning);
        }
        else
        {
            if (dataGridViewAFp1.Rows[0].Cells["Annual_Fees"].Value != null)
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;

                int.TryParse(dataGridViewAFp1.Rows[0].Cells["Annual_Fees"].Value.ToString(), out AF11);
                AF2 = Convert.ToInt32(txtp1AF.Text);
                ResultAF = AF11 + AF2;
                String updatedAF = Convert.ToString(ResultAF);

                cmd.CommandText = @"Update P1 set Annual_Fees=@af where Sponsorship_Status = 'Sponsored' OR Sponsorship_Status = 'Unsponsored' OR Sponsorship_Status = 'Formerly Sponsored' ";
                cmd.Parameters.AddWithValue("@af", updatedAF);
                cmd.ExecuteNonQuery();
                DataTable dt = new DataTable();
                SqlDataAdapter adap = new SqlDataAdapter(cmd);
                adap.Fill(dt);
                //dataGridViewAFp1.DataSource = dt;
                conn.Close();
                MessageBox.Show("Record Updated Successfully ");
                txtp1AF.Text = " "; 
            }

推荐答案

假设一切都正常在你身边，主要的问题是您使用的是 cmd 变量中包含的更新命令，您以前使用过更新数据库，尝试使用更新的值填充您的 dt 。相反，您必须使用为此目的选择命令，如下所示：

Assuming everything else is working fine on your side, the main problem is that you're using the same Update command contained in your cmd variable, that you used before to update the database, to try to fill your dt with the updated values. Instead you must use a Select command for that purpose, as follows:

更改：

DataTable dt = new DataTable();
SqlDataAdapter adap = new SqlDataAdapter(cmd);
adap.Fill(dt);
//dataGridViewAFp1.DataSource = dt;

到：

 DataTable dt = new DataTable();
 SqlDataAdapter adap = new SqlDataAdapter("select * from P1", conn);
 adap.Fill(dt);
 dataGridViewAFp1.DataSource = dt;

编辑：添加完整的工作代码。在此示例中，对于 100.00 到<$的前2个数据行，列 ListPrice （列索引9） c $ c> 200.00 （watch）。我正在使用您的代码，只需更改表和列名称。

Adding full working code. In this sample, column ListPrice (column index 9) is updated for the first 2 data rows from 100.00 to 200.00(watch). I'm using your code, just changing table and column names.

    private void btnEnterAFp1_Click(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\AdventureWorks2014.mdf;Integrated Security=True;Connect Timeout=30");
        decimal AF2;
        decimal AF11;
        decimal ResultAF;

        if (string.IsNullOrWhiteSpace(txtp1AF.Text))
        {

            MessageBox.Show("Please Enter fee", "Oops", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        }
        else
        {
            if (dataGridViewAFp1.Rows[0].Cells[9].Value != null)
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;

                decimal.TryParse(dataGridViewAFp1.Rows[0].Cells[9].Value.ToString(), out AF11);
                AF2 = Convert.ToDecimal(txtp1AF.Text);
                ResultAF = AF11 + AF2;
                String updatedAF = Convert.ToString(ResultAF);

                cmd.CommandText = @"Update Production.Product set ListPrice=@af where Name = 'Adjustable Race' OR Name = 'Bearing Ball'";
                cmd.Parameters.AddWithValue("@af", updatedAF);
                int n = cmd.ExecuteNonQuery();

                DataTable dt = new DataTable();
                SqlDataAdapter adap = new SqlDataAdapter("select * from Production.Product", conn);
                adap.Fill(dt);

                dataGridViewAFp1.DataSource = dt;

                conn.Close();
                MessageBox.Show("Record Updated Successfully ");
                txtp1AF.Text = " ";
            }
        }
    }

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