Please find inner join for more than 2 table here
Here are 4 table name like
So the SQL code would be:
select o.orderid, c.customername, l.lname, s.studadd, s.studmarks
from orders o
inner join customers c on o.customrid = c.customerid
inner join lecturer l on o.customrid = l.id
inner join student s on o.customrid=s.studmarks;