The DELETE operator is used to erase records (not table structure).  The number of records deleted may be 0, 1, or many, depending on how many satisfy the predicate.

Format:
DELETE FROM table/view WHERE delete_criteria;

Example 1

Erase the record of student ‘S1020’  (Delete a single tuple)
DELETE FROM STUDENT WHERE STUID = ‘S1020’;

Example 2

Erase all enrollment records for student ‘S1020’.  (Delete several tuples).
DELETE FROM ENROLL WHERE STUID = ‘S1020’;

Example 3

Erase all the class records.  (Deleting all the tuples from a table)
DELETE FROM CLASS;

Note that the table CLASS still exists, but is empty.  To remove the data and the table you use the DROP TABLE operator.

Example 4

Erase all enrollment records for Owen McCarthy.  (Delete with a subquery)
DELETE FROM ENROLL WHERE STUID = (SELECT STUID FROM STUDENT WHERE FNAME = ‘Owen’ AND LNAME = ‘McCarthy’);

In our database there is no such student, so no records are deleted from ENROLL.