Week 04 Lecture (5)

SQL vs DBMS engine

select ... from R where C
- find relevant tuples (satisfying C) in file for R
insert into R values(...)
- place new tuple in some page of file for R
delete from R where C
- find relevant tuples and "remove" from file for R
update R set ... where C
- find relevant tuples in file for R and "change" them