MySQL命令C＃

Question

我有我的網頁上的代碼

private object getJobID() 
     { 
      try 
      { 
       conn.Open(); 

       String latestJobID = @"SELECT MAX(jobId) + 1 FROM joborder"; 

       MySqlCommand cmd = new MySqlCommand(latestJobID, conn); 
       MySqlDataReader DR = cmd.ExecuteReader(); 

       while (DR.Read()) 
       { 
        return DR[0].ToString(); 
       } 
      } 
      catch (MySqlException ex) 
      { 
       System.Diagnostics.Debug.WriteLine("ERROR: " + ex.ToString()); 
      } 
      finally 
      { 
       conn.Close(); 
      } 
      return ""; 
     } 

的@"SELECT MAX(jobId) + 1 FROM joborder"不添加+ 1，如果我的表是空的，我怎麼能添加+ 1我如果的jobId我的表空，感謝

Answer 1

您可以在查詢

select COALESCE(MAX(jobId), 0) + 1 FROM joborder