4.28 숙제(지역번호 개수 상관없이 #처리)

내가푼것

select name, tel, replace(tel, substr(tel, 1, INSTR(tel,')')-1), '##')

from student

where length(substr(tel,1,INSTR(tel,')')-1)) = 2

UNION all

select name, tel, replace(tel, substr(tel, 1, INSTR(tel,')')-1), '###')

from student

where length(substr(tel,1,INSTR(tel,')')-1)) = 3;

선생님 답

select name,  tel,  

lpad(substr(tel, instr(tel,')',1)), 12, '##########') 

from student;