选择只有一个不同列的重复行并将其分组

Question

SELECT
    a.FirstName,
    a.LastName,
    c.Country,
    SUM(b.Scores) AS Score
FROM names a
INNER JOIN countries c
    ON a.id = c.cid
INNER JOIN scores b
    ON a.id = b.sid
WHERE a.id = :id
GROUP BY c.Country
ORDER BY Score ASC

我正在尝试使用此查询来select duplicated但具有不同countries行，因此从这些表中进行选择

           names                           countries                       scores
[id  --  FirstName  -- LastName]    [id --  cid  --  Country]      [id   --  sid  --  Score]
[1   --   FName1    --  LName1 ]    [1  --   1   --  USA    ]      [1    --   1   --      5] 
[2   --   FName2    --  LName2 ]    [2  --   1   --  France ]      [2    --   1   --      6]
[3   --   FName3    --  LName3 ]    [3  --   1   --  Germany]      [3    --   2   --      7]
[4   --   FName4    --  LName4 ]    [4  --   2   --  Germany]      [4    --   2   --      8] 
                                    [5  --   2   --  Czech  ]      [5    --   2   --      2]
                                    [6  --   3   --  Germany]      [6    --   4   --     10]
                                    [7  --   4   --  France ]      [7    --   3   --     15]

静力学应该是

{id[1] -> FName1 -> LName1}--{cid[1] -> USA, France, Germany}--{sid[1] -> 11}
{id[2] -> FName2 -> LName2}--{cid[2] -> Czech    ,   Germany}--{sid[2] -> 17}
{id[3] -> FName3 -> LName3}--{cid[3] ->        Germany      }--{sid[3] -> 10}
{id[4] -> FName4 -> LName4}--{cid[4] ->        France       }--{sid[4] -> 15}

我想获取这些数据，例如以下HTML结构

 .Container div { border: 1px solid blue; margin: 10px; } .Container div div { border: 1px solid red; margin: 10px; } 

 <div> <div id="Master German">German</div> <div id="German"> <div class="Container"> <div id='FName2 German'> <div>FName2</div> <div>LName2</div> </div> <div id='FName1 German'> <div>FName1</div> <div>LName1</div> </div> <div id='FName3 German'> <div>FName3</div> <div>LName3</div> </div> </div> </div> <div id="Master France">France</div> <div id="France"> <div class="Container"> <div id='FName4 France'> <div>FName4</div> <div>LName4</div> </div> <div id='FName1 France'> <div>FName1</div> <div>LName1</div> </div> </div> </div> <div id="Master Czech">Czech</div> <div id="Czech"> <div class="Container"> <div id='FName2 Czech'> <div>FName2</div> <div>LName2</div> </div> </div> </div> <div id="Master USA">USA</div> <div id="USA"> <div class="Container"> <div id='FName1 USA'> <div>FName1</div> <div>LName1</div> </div> </div> </div> </div> 

我尝试在查询中使用的是以下PHP代码

$pre = null;
echo "<div>";
$end = "";
while ($row = $stmt->fetch()) {
    $FName = $row['FirstName'];
    $LName = $row['LastName'];
    $Country = $row['Country'];

    if ($Country != $pre) {
        echo $end;
        echo "<div id='Master $Country'>$Country</div>";
        echo "<div id='$Country'>";
    }
    $end = "</div>
</div>";
    $pre = $Country;

    echo "
<div id='$FName USA'>
    <div>$FName</div>
    <div>$LName</div>
</div>";
}
echo $end;
echo "</div>";

但是，它根本无法按预期工作，并且让我头疼的要修复它，但是没有希望。

有没有更好的方法来解决这个问题？ 从SQL端或PHP端开始，或者尽可能混合使用。

Answer 1

通过“行”，我将您的问题解释为具有多个国家的names 。 如果是这样的话：

SELECT n.FirstName, n.LastName,
       GROUP_CONCAT(DISTINCT c.Country) as countries, SUM(s.Scores) AS Score
FROM names n INNER JOIN
     countries c
     ON n.id = c.cid INNER JOIN
     scores s
     ON n.id = s.sid
WHERE n.id = :id
GROUP BY n.id, n.FirstName, n.LastName
HAVING COUNT(DISTINCT c.country) > 1
ORDER BY Score ASC;