SQL计数的大小和性别

Question

我想算衬衫大小和每个尺寸必须表现出不同的性别

这里是输出我想看到

Size Qty Male Female 

S 20 15  5 
M 30 20 10 

这里是我的一些SQL语言和PHP代码，但是这只是查询每个大小的数量。

$stmt = $con->prepare("SELECT ssize,COUNT(*) FROM students GROUP BY ssize"); 

$stmt->execute(); 

<?php while($rs = $stmt->fetch()) { ?> 

    <?=$rs['ssize']." ".number_format($rs["COUNT(*)"])?> 

<?php } ?> 

Answer 1

为此，您可以使用条件汇总：

SELECT s.ssize, COUNT(*), 
     SUM(s.gender = 'M') as Male, SUM(s.gender = 'F') as Female 
FROM students s 
GROUP BY s.ssize;