用c#编码从mysql表填充数据的问题 [英] problem with c# coding to populate data from mysql table

问题描述

我用按钮制作一个文本框，以便在单击按钮时可以在该文本框中提供指定列的总和，必须在c#.plz帮助中完成

i m making a textbox with a button so that when button is clicked it gives sum of specified column in that textbox it has to be done in c#.plz help

MySqlConnection MyCon = new MySqlConnection("server=localhost; Database = nikz; user id=root; password=***; pooling=false;");
MyCon.Open();
MySqlCommand command = new MySqlCommand();
string SQL = "select sum(Actual_amt) from tds";
command.Connection = MyCon;
command.CommandText = SQL;
actamttxtbox.Text = SQL.ExecuteScalar();
command.ExecuteNonQuery();
MyCon.Close();

这就是我所做的，并且给出了错误

this is what i hav done and is giving errors

推荐答案

变量SQL 是一个字符串. string 没有方法ExecuteScalar()

改变

variable SQL is a string. A string has no method ExecuteScalar()

change

actamttxtbox.Text = SQL.ExecuteScalar();

到

to

actamttxtbox.Text = (string)command.ExecuteScalar();

而且您不需要cmd.ExecuteNonQuery();



我已经整理了一下:

And you don''t need cmd.ExecuteNonQuery();



I''ve cleaned up a little bit:

MySqlConnection conn = new MySqlConnection("connection-string");
conn.Open();

using(MySqlCommand cmd = new MySqlCommand()){
  cmd.Connection = conn;
  cmd.CommandText = "select sum(Actual_amt) from tds";
  actamttxtbox.Text = cmd.ExecuteScalar().ToString();
}
conn.Close();

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