Question

我正在研究一个公式，我在行和列中添加多个值，具体取决于其他单元格的值。例如，我有以下工作代码：

$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，这些列也是其他行/列的总和，并且不知道如何执行此操作，同时仍然保留按“学校”列分组的所有内容。我基本上想要的是以下内容，但代码不正确：

$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，所以我不确定正确/最佳的设置方法。感谢

Answer 1

这是您应该使用的查询来获得2个总计：

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;

根据event列了解它的添加方式？诀窍是通过条件执行（WHERE）在SELECT子句中传递IF过滤器

使用CASE WHEN的其他可能性：

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;

PHP MySQL查询 - 添加

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