Creating Sequences

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A sequence can be used to provide the default value for a table column or a domain, etc.

A sequence returns a series of integer values which is defined by a start value, a minimum value, a maximum value, an increment and whether the sequence is to be cyclic or not.

A sequence that has been initialized has a current value, which is returned from the function CURRENT VALUE. The function NEXT VALUE is used to initialize a sequence and to subsequently advance the current value of the sequence through its defined series of values.

A no cycle sequence will never return the same value twice.

Examples of Sequences

Create a sequence that returns odd numbers:

 CREATE SEQUENCE seq_1 START WITH 1 INCREMENT BY 2 IN userdb;

Create a sequence that defines the following series of values: 1, 4, 7, 10:

 CREATE SEQUENCE seq_2
    START WITH 1
    INCREMENT 3
    MAXVALUE 10
    NO CYCLE
 IN DATABANK userdb;

Create a table that uses a sequence to set a column default value:

 CREATE TABLE objinfo (objid INTEGER DEFAULT NEXT VALUE FOR obj_seq,
                       description NCHAR VARYING(1000));

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