If-else else where where 절

Question

IF 조건에 따라 where 절을 변경하려고합니다. 어떤 이유로 쿼리가 실패합니다. 나는 어떤 도움을 주셔서 감사합니다.

감사합니다.

 SELECT 
      c.id AS course, 
      cr.id AS criteriaid, 
      u.id AS userid, 
      ue.timestart AS otimestart, 
      (ue.timestart + cr.enrolperiod) AS ctimestart, 
      ue.timecreated AS otimeenrolled, 
      (ue.timecreated + cr.enrolperiod) AS ctimeenrolled 
     FROM 
      {user} u 
     INNER JOIN 
      {user_enrolments} ue 
     ON ue.userid = u.id 
     INNER JOIN 
      {enrol} e 
     ON e.id = ue.enrolid 
     INNER JOIN 
      {course} c 
     ON c.id = e.courseid 
     INNER JOIN 
      {course_completion_criteria} cr 
     ON c.id = cr.course 
     LEFT JOIN 
      {course_completion_crit_compl} cc 
     ON cc.criteriaid = cr.id 
     AND cc.userid = u.id 
     WHERE 
      cr.criteriatype = 5 
     AND c.enablecompletion = 1 
     AND cc.id IS NULL 
     AND    
     (
     IF (ue.timeextension IS NULL) 
       (ue.timestart > 0 AND ue.timestart + cr.enrolperiod < ? 
      OR ue.timecreated > 0 AND ue.timecreated + cr.enrolperiod < ?) 
     ELSE 
       (ue.timestart > 0 AND ue.timestart + ue.timextension < ? 
      OR ue.timecreated > 0 AND ue.timecreated + ue.timeextension < ?) 
     ) 

Answer 1

당신이 올바른 수행하려는 작업에 따라 절을 수 있습니다 여기서

이

... 
where ... 
and (if(ue.timeextension IS NULL, 
     ue.timestart > 0 AND ue.timestart + cr.enrolperiod < ? 
      OR ue.timecreated > 0 AND ue.timecreated + cr.enrolperiod < ?, 
     ue.timestart > 0 AND ue.timestart + ue.timextension < ? 
      OR ue.timecreated > 0 AND ue.timecreated + ue.timeextension < ?); 

Answer 2

IF 식의 구문은 다음과 같습니다

IF(<cond-expr>, <then-expr>, <else-expr>) 

가에는 ELSE 키워드가 없습니다 구문을 사용하면 두 결과 표현식을 쉼표로 구분하면됩니다. 그래서 표현의 올바른 구문이되어야합니다 :

AND IF(ue.timeextension IS NULL, 
     (ue.timestart > 0 AND ue.timestart + cr.enrolperiod < ?) 
     OR (ue.timecreated > 0 AND ue.timecreated + cr.enrolperiod < ?), 
     (ue.timestart > 0 AND ue.timestart + ue.timextension < ?) 
     OR (ue.timecreated > 0 AND ue.timecreated + ue.timeextension < ?)) 

이 쓸 수있는 또 다른 방법은 다음과 같습니다

AND ((ue.timestart > 0 AND ue.timestart + IFNULL(ue.timeextesion, cr.enrolperiod) < ?) 
    OR (ue.timecreated > 0 AND ue.timecreated + IFNULL(ue.timeextesion, cr.enrolperiod)) < ?) 

Answer 3

나는 당신이 지난 섹션을 시도 할 수 있습니다 생각하는 경우 즉,

AND    
    (
    IF (ue.timeextension IS NULL) 
      (ue.timestart > 0 AND ue.timestart + cr.enrolperiod < ? 
     OR ue.timecreated > 0 AND ue.timecreated + cr.enrolperiod < ?) 
    ELSE 
      (ue.timestart > 0 AND ue.timestart + ue.timextension < ? 
     OR ue.timecreated > 0 AND ue.timecreated + ue.timeextension < ?) 
    ) 

로

AND    
    (
     (ue.timestart > 0 AND ue.timestart + 
      IFNULL(ue.timeextension , cr.enrolperiod) < ?) 
    OR (ue.timecreated > 0 AND ue.timecreated + 
      IFNULL (ue.timeextension, cr.enrolperiod) < ?) 
    )