小编use*_*814的帖子

我有一个应用程序C#连接并在数据库中做一些事情,所以我需要在表中找到一个序列号并返回它,我这样做但我有一个问题:

public int Select_Begin(string serial)
{
   string query = "SELECT serial FROM `compteur_mono` WHERE   serial = " + serial + ";";
   //Open connection
   MySqlCommand cmd = new MySqlCommand(query, connection);
   if (this.OpenConnection() == true)
   {
      int numero = cmd.ExecuteNonQuery();
      return numero;
   }
   else
   {
      return 0;
   }
}

当我执行时,结果总是-1但是当我这样做时:

public string Select_Begin(string serial)
{
   string query = "SELECT serial FROM `compteur_mono` WHERE   serial = " + serial + ";";
   //Open connection
   MySqlCommand cmd = new MySqlCommand(query, connection);
   if (this.OpenConnection() == true) …