如何計算出勤率

Question

我想要統計每個學生的總出勤率。我有兩張獨立的桌子，我在學生桌上保留了學生的姓名和身份證，並在出席表上保留出席人數和身份證。在參加座位表上，我爲每個學生以及1個和0個30個行。我想列出每個學生列出名稱的出勤率（總共爲0）。應該是什麼樣的SQL？感謝您的幫助

$sql="SELECT * FROM students LEFT JOIN attendance ON students.KategoriID = attendance .KategoriID where WHERE attendance =0 "; 
$sonuc = mysql_query ($sql) ; 
while($satir=mysql_fetch_array($sonuc)) { 

Answer 1

QUERY：

SELECT student.*, count(attendance.attendance) AS absent FROM student 
LEFT JOIN attendance ON student.KategoriID =attendance.KategoriID 
AND attendance.attendance=0 GROUP BY attendance.KategoriID ORDER BY  
student.KategoriID; 

嘗試此查詢。

檢查SQL FIDDLE