multiple table inner join didn't get expected values
Suppose that you want sem3 then query will be

Case 1# 

Select stureg.regno,stureg.pro,stureg.name,stureg.start_day,
sem.regno,sem.curSemmester,sem.name
from student_register as stureg left outer join semester as sem on stureg.regno=sem.regno
where stureg.pro REGEXP '^H' and sem.CurSemmester='3'

group by regno

order by regno
;


Case 2#

Select stureg.regno,stureg.pro,stureg.name,stureg.start_day,
sem.regno,sem.curSemmester,sem.name
from student_register as stureg left outer join semester as sem on stureg.regno=sem.regno
where stureg.pro like '%H%' and sem.CurSemmester='3'

group by regno

order by regno
;


Give it Try.