mysql - 查询总和(总计)

Question

exchanges表结构:

  id   exchange       created_at            updated_at        deleted_at   start_time   close_time  
 ---- ---------- --------------------- --------------------- ------------ ------------ ------------ 
   1   NSE        2018-04-18 06:22:11   2018-04-18 06:22:11   (NULL)       09:15:00     03:30:00    
   2   BSE        2018-05-06 07:07:53   2018-05-06 07:07:53   (NULL)       00:00:00     00:00:00    
   3   NYSE       2018-05-19 08:34:07   2018-05-19 08:34:07   (NULL)       00:00:00     00:00:00    

finaltrades 表结构:

  id   user_id   exchange_id   market_id   symbol_id      buy_datetime          sell_datetime      buy_rate   sell_rate   quantities  
 ---- --------- ------------- ----------- ----------- --------------------- --------------------- ---------- ----------- ------------ 
   1         1             1           1          96   2018-05-25 18:13:26   0000-00-00 00:00:00       2205           0          100  
   2         1             1           1          96   0000-00-00 00:00:00   2018-05-25 18:13:59          0        6680          100  
   3         4             1           1          23   2018-05-25 18:16:27   0000-00-00 00:00:00          0           0           10  
   4         1             1           1          96   2018-05-25 18:13:59   0000-00-00 00:00:00      50351           0           30  
   5         1             1           1          15   0000-00-00 00:00:00   2018-05-25 18:34:46          0         100          150  
   6         4             1           1         573   2018-05-26 09:29:17   2018-05-27 03:10:09         10          10           10  
   7         1             1           1          15   2018-05-11 09:30:54   2018-05-25 18:34:56         40         100           40

<小时/>

我想减去buy_datetime - sell_datetime = hours，将该计算应用于所有行并将所有结果加在一起。

例如，

buy_datetime - sell_datetime = 12 hours
buy_datetime - sell_datetime = 19 hours
buy_datetime - sell_datetime = 11 hours

现在

total all = 32 hours

这是我到目前为止想到的

public function total_hours_count {

    $first_hour_trade = DB::table('finaltrade')            
                                 ->select('finaltrade.*')               
                                 ->where('buy_datetime','-','sell_datetime')
                                 ->sum() -> get();
            
    return response() -> json($first_hour_trade);
}

不知道代码错误在哪里。

Answer 1

如果您想总结整个表中 buy_datetime 和 sell_datetime 的差异，您可以使用原始表达式

DB::table('finaltrade')
    ->select(DB::raw("SUM(TIME_TO_SEC(TIMEDIFF(buy_datetime, sell_datetime )) / 3600) AS total_hours")
    ->get();