Deletion

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

   

   where is a relation and is a relational algebra query.

   Tuples in for which is true are deleted.

2. Some examples:

   1. Delete all of Smith's account records.

   

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

   

   3. Delete all accounts at Branches located in Needham.