c# - 为什么不更新我的数据？

Question

更新组时出错。必须声明标量变量“@SubnameWHERE”...为什么显示此错误......

protected void cmdUpdate_Click(object sender, EventArgs e)
    {
        string updateSQL;
        updateSQL = "UPDATE tblnewgroup SET ";
        updateSQL += "Groupname=@Groupname, ";
        updateSQL += "Slno=@Slno, Subname=@Subname";
        updateSQL += "WHERE Groupno=@Groupno_original";

    SqlConnection con = new SqlConnection(connectionString);
    SqlCommand cmd = new SqlCommand(updateSQL, con);


    cmd.Parameters.AddWithValue("@Groupname", txtgname.Text);
    cmd.Parameters.AddWithValue("@Slno", txtsl.Text);
    cmd.Parameters.AddWithValue("@Subname", txtsn.Text);
    cmd.Parameters.AddWithValue("@Groupno_original", lstAuthor.SelectedItem.Value);

    int updated = 0;
    try
    {
        con.Open();
        updated = cmd.ExecuteNonQuery();
        lblResults.Text = updated.ToString() + " record updated.";
    }
    catch (Exception err)
    {
        lblResults.Text = "Error updating Group. ";
        lblResults.Text += err.Message;
    }
    finally
    {
        con.Close();
    }

    if (updated > 0)
    {
        FillAuthorList();
    }

}

Answer 1

Subname=@Subname 后需要一个空格

改变你的

updateSQL += "Slno=@Slno, Subname=@Subname";

到

updateSQL += "Slno=@Slno, Subname=@Subname ";

作为更好的可视化，你可以像这样使用它；

string updateSQL = @"UPDATE tblnewgroup
                     SET Groupname=@Groupname, Slno=@Slno, Subname=@Subname
                     WHERE Groupno=@Groupno_original";

您还应该使用 using阻止处理你的 SqlConnection，例如；

using(SqlConnection con = new SqlConnection(connectionString))
{
  con.Open();
  updated = cmd.ExecuteNonQuery();
  ...
}