Question

Describe the characteristics of an Oracle sequence.

Answer 1

Oracle is the leading manufacturer of customized database management software. Oracle databases have a lot of useful features and functionalities to aid the user to carry out meaningful tasks with utter ease.

One of the key features of the Oracle database is a sequence. A Sequence as the name suggests is a machine-generated series of sequential numbers that is used to assign unique and concrete(not null) values.

These Oracle sequences help the user to define constraints like PRIMARY KEY that can be auto-incremented, helps the user handle duplication and avoid redundant data in the database.

Some of the characteristics of Oracle sequences are:

(1) A Sequence is typically a database object with unique values (meaning no two values can be the same).

(2) Sequences can be customized and used with almost any other database object.

(3) Sequences can be stored in local memory (meaning they can be cached).

(4) Sequences for a particular table are robust and independent ( meaning one can use the same sequence in another database table).

(5) Sequences are accessible database objects (meaning the value of a sequence can be accessed and manipulated by a set of commands like CURRVAL and NEXTVAL ).

(6) Sequences are independent of native transactional database operations like COMMIT, ROLLBACK, etc.

(7) Existing sequences can be altered and modified if necessary privileges are set within a database.

Example of creating a sequence:

CREATE SEQUENCE student_sequence
              START WITH 1

              INCREMENT BY 1

              NOCYCLE

              NOMAXVALUE

              CACHE 20;