Q) What is sequence ? Write and explain the syntax ‘CREATE SEQUENCE’ statements.

ANS:  Sequence :-                                    

·      A Sequence is a set of integers (1,2,3…) that is used to generate a number sequence.

·      Sequence is useful when need to create a unique number to act as a primary key.

·       The sequence of numeric values is generated in ascending or descending order.

 

              Syntax-

 

CREATE SEQUENCE seq_name

START WITH initial_val

INCREMENT BY inc_val / DECREMENT BY dec_value

MAXVALUE  max_val

CYCLE / NOCYCLE ;

 

 

           Example-1

  

CREATE SEQUENCE seq_1

START WITH 1

INCREMENT BY 1

MAXVALUE   999

CYCLE ;

 

  §   INITIAL VALUE :- Specifies the starting value for the sequence.

  §  INCREMENT VALUE :- Value by which sequence will  be incremented.

  §  MAXIMUM VALUE :- Specifies the upper limit / maximum value.

  §  CYCLE :- Specifies that the value reaching either its MIN/MAXVALUE, sequence will restart its cycle from begining.

  §  NOCYCLE :- Specifies to indicate that the sequence can’t generate more value after reaching                                                         its MIN/MAXVALUE.