如何從一數列與行不同的價值

Question

我有一個問題的探析與不同的數從一列行，這裏是我的數據庫和查詢

$host = 'localhost'; 
$db = 'cbt'; 
$user = 'root'; 
$pass = ''; 

$dsn = "mysql:host=$host;dbname=$db"; 
$pdo = new PDO($dsn, $user, $pass); 

$matematika = 'MTK'; 
$soal_mtk = $pdo->prepare("select count(*) from cbt.data_ujian where data_ujian.id_mapel = :mtk"); 
$soal_mtk->bindParam(':mtk', $matematika, PDO::PARAM_STR, 12); 
$soal_mtk->execute(); 
$mtk = $soal_mtk->fetchColumn(); 

$fisika = 'FIS'; 
$soal_fis = $pdo->prepare("select count(*) from cbt.data_ujian where data_ujian.id_mapel = :fis"); 
$soal_fis->bindParam(':fis', $fisika, PDO::PARAM_STR, 12); 
$soal_fis->execute(); 
$fis = $soal_fis->fetchColumn(); 

$kimia = 'KIM'; 
$soal_kim = $pdo->prepare("select count(*) from cbt.data_ujian where data_ujian.id_mapel = :kim"); 
$soal_kim->bindParam(':kim', $kimia, PDO::PARAM_STR, 12); 
$soal_kim->execute(); 
$kim = $soal_kim->fetchColumn(); 

我可以指望這一切與一個查詢？請告訴我是否需要更多信息。謝謝你以前這麼多。

Answer 1

當然可以，你需要使用GROUP BY與WHERE條件。與此類似，

SELECT count(*), 
     data_ujian.id_mapel 
FROM cbt.data_ujian 
WHERE (data_ujian.id_mapel = :mtk 
     OR data_ujian.id_mapel = :fis 
     OR data_ujian.id_mapel = :kim) 
GROUP BY data_ujian.id_mapel 

上面的語句將組的結果通過id_mapel列，並給每個類別的count。

Answer 2

如果我理解你的權利GROUP BY子句應該做你要求什麼：

SELECT count(*), id_mapel FROM cbt.data_ujian GROUP BY id_mapel 

Answer 3

嘗試下面的查詢 -

SELECT Sum(data_ujian.id_mapel = 'mtk') AS 'mtk', 
     Sum(data_ujian.id_mapel = 'fis') AS 'fis', 
     Sum(data_ujian.id_mapel = 'kim') AS 'kim', 
FROM cbt.data_ujian;