PHP MySQL查詢-添加

Question

我正在研究一個公式，其中根據其他單元格的值在行和列中添加多個值。 例如，我有以下工作代碼：

$result = mysql_query("SELECT School,SUM(Wins + Losses) as total FROM tennis GROUP BY School");
 echo "<table border='1'>
<tr>
<th>School</th>
<th>Score</th>
</tr>";

while($row = mysql_fetch_array($result))
  {
  echo "<tr>";
  echo "<td>" . $row['School'] .  "</td>";
  echo "<td>" . $row['total'] .  "</td>";
  echo "</tr>";
  }

但是我想添加更多的列，這些列也是其他行/列的總和，並且不知道如何做到這一點，同時仍將所有內容按“學校”列分組。 我本質上想要的是以下內容，但是代碼不正確：

$result = mysql_query("SELECT School,SUM(Wins + Losses) as 1sttotal FROM tennis WHERE Event='1st Singles', SUM(Wins + Losses) as 2ndtotal FROM tennis WHERE Event='2nd Singles' GROUP BY School");
 echo "<table border='1'>
<tr>
<th>School</th>
<th>1st Singles</th>
<th>2nd Singles</th>
</tr>";

while($row = mysql_fetch_array($result))
  {
  echo "<tr>";
  echo "<td>" . $row['School'] .  "</td>";
  echo "<td>" . $row['1sttotal'] .  "</td>";
  echo "<td>" . $row['2ndtotal'] .  "</td>";
  echo "</tr>";
  }

我是PHP的新手，所以我不確定要進行正確設置的正確/最佳方法。 謝謝

Answer 1

這是您應該用來獲取2個總數的查詢：

SELECT 
    School,
    SUM(IF(Event='1st Singles', Wins + Losses, 0)) as 1sttotal,
    SUM(IF(Event='2nd Singles', Wins + Losses, 0)) as 2ndtotal
FROM tennis 
GROUP BY School;

看看它如何根據event列添加？ 訣竅是通過條件執行（ IF ）在SELECT子句中傳遞WHERE過濾器

使用CASE WHEN其他可能性：

SELECT 
    School,
    SUM(
        CASE 
            WHEN Event='1st Singles' THEN Wins + Losses
            ELSE 0
        END
    ) as 1sttotal,
    SUM(
        CASE 
            WHEN Event='2nd Singles' THEN Wins + Losses
            ELSE 0
        END
    ) as 2ndtotal
FROM tennis 
GROUP BY School;