mySql不明な列

Question

次のクエリがあります

    SELECT 
     s.name, 
     s.surname, 
     s.id_nr, 
     s.student_nr, 
     s.createdate, 
     s.enddate, 
     (SELECT count(*) FROM Student_Attendance WHERE absent = 1) AS count_absent 
    FROM 
     Student AS s, 
     Student_Contact AS sc, 
     Student_Payment AS p, 
     Student_Courses AS scou, 
     Modules AS m, 
     Student_Certificate AS scer, 
     Student_Results AS sr, 
     Lecturer_Profile AS l, 
     Lecturer_Comments AS lc, 
     Student_Attendance AS sa, 
     Student_Training AS t 
    WHERE s.s_id = sc.s_id 
    AND s.s_id = p.s_id 
    AND s.s_id = scou.s_id 
    AND scou.c_id = m.c_id 
    AND s.s_id = scer.s_id 
    AND s.s_id = sr.s_id 
    AND s.s_id = lc.s_id 
    AND lc.l_id = l.l_id 
    AND s.s_id = sa.s_id 
    AND LOWER(s.name) = 'andile' 
    AND LOWER(s.surname)  = ' orson vulture' 
    AND s.id_nr = 8403125062671 
    AND LOWER(sc.race) = 'white' 
    AND sc.gender = 1 
    AND LOWER(sc.area) = 'gauteng' 
    AND p.payment_type = 1 
    AND s.student_nr = 203087506 
    AND scou.c_id = 1 AND sc.age = 23 
    AND scer.certificate_number = 3424234 
    AND sr.result = 32 
    AND l.l_id= 1 
    AND count_absent = 3 
    AND LOWER(s.branch) = 'pretoria' 
    AND LOWER(s.campus_name) = 'pretoria' 
    AND LOWER(sc.kin_name) = 'self' 
    AND t.s_id = s.s_id 
    AND t.sp_id = 1 

次のエラーが表示されます

CDbCommand failed to execute the SQL statement: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'count_absent' in 'where clause'

列はselectステートメントにあるため、これを解決する方法がわからない

Answer 1

派生列count_absentは、WHERE句の後に処理されるSELECT句で処理されるため、使用できません。クエリ全体を外側のSELECTでラップすると、派生列にアクセスできるようになります。

i.e。

select * from (
SELECT 
 s.name, 
 s.surname, 
 s.id_nr, 
 s.student_nr, 
 s.createdate, 
 s.enddate, 
 (SELECT count(*) FROM Student_Attendance WHERE absent = 1) AS count_absent 
FROM 
 Student AS s, 
 Student_Contact AS sc, 
 Student_Payment AS p, 
 Student_Courses AS scou, 
 Modules AS m, 
 Student_Certificate AS scer, 
 Student_Results AS sr, 
 Lecturer_Profile AS l, 
 Lecturer_Comments AS lc, 
 Student_Attendance AS sa, 
 Student_Training AS t 
WHERE s.s_id = sc.s_id 
AND s.s_id = p.s_id 
...
AND t.s_id = s.s_id 
AND t.sp_id = 1
) as x where count_absent = 3

Answer 2

ここで何を達成しようとしているのかわかりませんが、count_absentを提供する埋め込みクエリは「absent = 1」以外の基準を使用しないことに注意してください。したがって、あなたがどの学生を見ているかに関係なく、absent = 1のすべてのstudent_attendanceレコードのカウントを常に取得します。これを、選択した学生のstudent_attendanceレコードに制限する必要があると思われます。

また、「参加」を調査することもできます。句。これにより、クエリがより簡単になり、古いスタイルがwhereに結合されます。