Simple MySql function example for return data from table using Id

1)table student

studentno varchar(50)

hobby1 varchar(40);

hobby2 varchar(40);

hobby3  varchar(40);

2)if record in data database such that

hobby1  hobby2   hobby3 in this maximum is one must be chose

like

here  studentno  hobby1  hobby2   hobby3

           1             cricket   null         null      

           2             null      hockey     null

           3             null       null        tennis

if i want to write function in mysql if i pass the studentno

i want to get the hobby of respective student

like select functionname(1)

your hobby is cricket

like select functionname(2)

your hobby is hockey

ike select functionname(3)

your hobby is tennis