如何在Gridview中更新选定的行？

Question

I have a TextBox with id=txtPlace and a gridview. If a user selects a row an put some Information in the TextBox and click on save. The Information should replace older records in the database(SQL)

  protected void btnSave_Click(object sender, EventArgs e) { var id = GridView2.SelectedDataKey.Values[0].ToString(); string constr = ConfigurationManager.ConnectionStrings["con"].ConnectionString; using (SqlConnection conn = new SqlConnection(constr)) { string query = "UPDATE user SET place= @place where ID = @ID "; SqlCommand cmd = new SqlCommand(query, conn); cmd.Parameters.AddWithValue("@place", txtPlace.Text); cmd.Parameters.AddWithValue("@ID", id); } } 

But It does not work. When I click on save, nothing happens.

Answer 1

You're missing a couple crucial steps - opening the SqlConnection and executing the SqlCommand . Since this is something where you don't expect a result back, you can just use ExecuteNonQuery() . You probably should wrap SqlCommand in a using block as well, since it's IDisposable , and your variable is incorrectly named.

protected void btnSave_Click(object sender, EventArgs e)
{
    var id = GridView2.SelectedDataKey.Values[0].ToString();
    string constr = ConfigurationManager.ConnectionStrings["con"].ConnectionString;
    using (SqlConnection conn = new SqlConnection(constr))
    {
        conn.Open(); // actually connect to the server
        string query = "UPDATE user SET place= @place where ID = @ID "; // change @D to @ID
        using (SqlCommand cmd = new SqlCommand(query, conn))
        {
            cmd.Parameters.AddWithValue("@place", txtPlace.Text);
            cmd.Parameters.AddWithValue("@ID", id);
            cmd.ExecuteNonQuery(); // actually execute your statement
        }
    }
}

Answer 2

string query = "UPDATE user SET place= @place where ID = @D ";

我猜您输入了错误的变量名，看起来@D与@ID不同