A sequence is a schema object that can generate unique sequential values. These values are often used for primary and unique keys. You can refer to sequence values in SQL statements with these pseudocolumns:
• CURRVAL: Returns the current value of a sequence
• NEXTVAL: Increments the sequence and returns the next value
You must qualify CURRVAL and NEXTVAL with the name of the sequence:
sequence.CURRVAL
sequence.NEXTVAL
To refer to the current or next value of a sequence in the schema of another user, you must have been granted either SELECT object privilege on the sequence or SELECT ANY SEQUENCE system privilege, and you must qualify the sequence with the schema containing it:
schema.sequence.CURRVAL
schema.sequence.NEXTVAL
To refer to the value of a sequence on a remote database, you must qualify the sequence with a complete or partial name of a database link:
schema.sequence.CURRVAL@dblink
schema.sequence.NEXTVAL@dblink
A sequence can be accessed by many users concurrently with no waiting or locking.
