A cursor is a control structure used to traverse and process database records in a result set. Every SQL statement
involves the use of a cursor. Since PL/SQL is tightly integrated with SQL, the ability to reference and control cursors is
a significant feature of the language. Cursors can be explicit or implicit. An implicit cursor is used
when assigning a value to a variable using the SELECT INTO syntax. An implicit cursor is also created
when a DML statement (INSERT/UPDATE/DELETE) is executed. An explicit cursor must be declared for SQL statements that
return more than one row.