Oracle Create Sequence tips

Oracle Create Sequence

The oracle docs note the syntax for the Oracle CREATE SEQUENCE function as follows:

CREATE SEQUENCE [ schema. ]sequence

Let's look at this example for using the Oracle CREATE SEQUENCE:

SQL> create sequence pubs1;

Sequence created.

In the example above, we used CREATE SEQUENCE to create a sequence called pubs1.  We use the NEXTVAL function to retrieve the next value.  You can get the current value by calling the CURRVAL function.   You must call the NEXTVAL function before calling the CURRVAL function, or you will get an error.  There is no current value to the sequence until the next value has been called at least once.

When you use Oracle CREATE SEQUENCE to create the sequence, you have a lot of flexibility as to how the sequence generates the next number.

SQL> create sequence pubs2
  2  start with 8
  3  increment by 2
  4  maxvalue 10000
  5  cycle
  6  cache 5; 

Sequence created.

SQL> select pubs2.nextval from dual; 

   NEXTVAL
----------
         8 

In this example, using Oracle CREATE SEQUENCE, the sequence pubs2 will start at number eight and increment by twos to 10000 and then start over.  Let's cover each of their parameters:

Related CREATE SEQUENCE articles:

Oracle Sequences Tips

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The above book excerpt is from:

Easy Oracle SQL

Get Started Fast writing SQL Reports with SQL*Plus

ISBN 0-9727513-7-8

John Garmany 

http://www.rampant-books.com/book_0501_easy_sql.htm

 

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