Mysql Group by With Condition - mysql

Question

The below data shows time schedule having elective/ non-elective subjects of a student. My requirement is to select those rows when both elec and nonelec type has same period so in this case select elec type. Means for a day's schedule elective (type elec) should be given preference when both having same period. And when type elec does not has period like period 5 then select the non-elective one.
My Query
SELECT s.sch_id, s.sch_subtype, sd.sdetail_id, sd.sdetail_period
FROM schedule s
INNER JOIN schedule_detail sd ON s.sch_id = sd.sdetail_schedule
WHERE '2014-04-30'
BETWEEN sch_datefrom
AND sch_dateto
AND
(
(
sch_section =1
AND sch_subtype = 'nonelec'
)
OR
(
sch_subtype = 'elec'
AND 272
IN
(
SELECT edetail_stuid
FROM elective_detail
WHERE edetail_elective = sch_section
)
)
)
AND sch_course =3
AND sch_batch =2
AND sch_termid =2
AND sdetail_day = 'wed'
AND sdetail_period >0
AND CASE WHEN sch_subtype = 'nonelec'
THEN 1 =1
WHEN sch_subtype = 'elec'
THEN sdetail_subject >0
AND sdetail_faculty >0
AND sdetail_room >0
END GROUP BY CASE WHEN sch_subtype = 'elec'
THEN sdetail_period
ELSE 1
END ORDER BY sdetail_period
Output of above query
Required Output

Answer 1

You can try something of this sort :
SELECT sch_id,sch_subtype,sdetail_id,sdetail_period
FROM table
WHERE condition
group by sch_subtype
It would be better if you can post the query which u tried.

Answer 2

Dont really get whats the problem here:
SELECT * FROM schedule s
JOIN schedule_detail sd ON s.sch_id = sd.sdetail_schedule
LEFT JOIN elective_detail ed ON sd.sch_section = ed.edetail_elective
WHERE
(
sd.sch_section =1
AND s.sch_subtype = 'nonelec'
)
OR
(
ed.edetail_stuid = 227
AND sch_subtype = 'elec'
)
GROUP BY sd.sdetail_period
SQL Fiddle: http://sqlfiddle.com/#!2/69d4e/1