1. Deletion is expressed in much the same way as a query. Instead of displaying, the selected tuples are removed from the database. We can only delete whole tuples.

In relational algebra, a deletion is of the form

r  r _E
where r is a relation and E is a relational algebra query. Tuples in r for which E is true are deleted.

2. Some examples:

1. Delete all of Smith's account records.

deposit deposit cname="Smith"(deposit)

2. Delete all loans with loan numbers between 1300 and 1500.

depositdeposit_loan#≥1300∧loan#≤1500(deposit)

3. Delete all accounts at Branches located in Needham.

r1city="Needham"(deposit∝branch)
r2bname,account#,cname,balance(r1)
deposit deposit_r2