NEXTVAL
Returns the next value in a sequence. Call NEXTVAL after creating a sequence to initialize the sequence with its default value. Thereafter, call NEXTVAL to increment the sequence value for ascending sequences, or decrement its value for descending sequences.
Syntax
NEXTVAL ('[[database.]schema.]sequence')
Parameters
- [- database- .]- schema
- Database and schema. The default schema is - public. If you specify a database, it must be the current database.
- sequence
- Identifies the target sequence.
Privileges
- 
SELECT privilege on sequence 
- 
USAGE privilege on sequence schema 
Restrictions
You cannot invoke NEXTVAL in a SELECT statement, in the following contexts:
- 
WHERE clause 
- 
GROUP BY clause 
- 
ORDER BY clause 
- 
DISTINCT clause 
- 
UNION 
- 
Subquery 
You also cannot invoke NEXTVAL to act on a sequence in:
- 
UPDATE or DELETE subqueries 
- 
Views 
You can use subqueries to work around some of these restrictions. For example, to use sequences with a DISTINCT clause:
=> SELECT t.col1, shift_allocation_seq.NEXTVAL FROM (
     SELECT DISTINCT col1 FROM av_temp1) t;
Examples
See Creating and using named sequences.