query: 取 3 条记录，哪条记录值大

Question

我想获取 3 个 symbol_id 具有更高的 buy_rate 值

finaltrades table 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       500        6680          100  
   3         4             1           1          23   2018-05-25 18:16:27   0000-00-00 00:00:00        120           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       750         100          150  
   6         4             1           1         573   2018-05-26 09:29:17   2018-05-27 03:10:09       107          10           10  
   7         1             1           1          15   2018-05-11 09:30:54   2018-05-25 18:34:56         40         100           40

这是我到目前为止的想法：

public function HigherValue(){
            
            $higher_value = DB::table('finaltrade')
                          ->select 'buy_rate'> (select 'buy_rate')
                          ->get();
                         
             return response()->json($higher_value);
             }

Answer 1

public function HigherValue() 
{
     $higher_value = DB::table('finaltrade')
         ->select('symbol_id')
         ->orderByDesc('buy_rate')
         ->limit(3)
         ->get();

     return response()->json($higher_value);
}

试试这个

Answer 2

试试这个

public function HigherValue() 
{
     $higher_value = DB::table('finaltrade')
         ->select('symbol_id')
         ->orderBy('buy_rate', 'DESC')
         ->limit(3)
         ->get();

     return response()->json($higher_value);
}

Answer 3

如果您想要三个不同的 symbol_id 具有最高的购买率，那么您可以尝试以下操作：

public function HigherValue() {
    $higher_value = DB::table('finaltrade')
        ->select('symbol_id')
        ->groupBy('symbol_id')
        ->orderByRaw('MAX(buy_rate) DESC')
        ->limit(3)
        ->get();

    return response()->json($higher_value);
}

这将对应于以下原始 MySQL 查询：

SELECT symbol_id
FROM finaltrade
GROUP BY symbol_id
ORDER BY MAX(buy_rate) DESC
LIMIT 3;

Answer 4

您可以使用 DISTINCT 来获得按 buy_rate

排序的不同 symbol_ids

SELECT DISTINCT symbol_id
FROM finaltrade
ORDER BY buy_rate DESC
LIMIT 3;

Demo

DB::table('finaltrade')
    ->orderBy('buy_rate', 'desc')
    ->distinct()
    ->limit(3)
    ->get();

query: 取 3 条记录，哪条记录值大

query: fetch 3 records which has higher value

mysql

laravel

laravel-5.3