PostgreSQL No Auto Increment function?

I have a test application coded in Java for creating an indexed and non indexed table in a MySQL, PostgreSQL, Oracle and Firebird database (Amongst other things).

Is it simply a case that PostgreSQL doesnt allow the auto increment feature? If not, what is th开发者_运维百科e normal procedure for having an indexed coloumn?

Thanks in advance

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You may use SERIAL in PostgreSQL to generate auto increment field,

For eg:-

CREATE TABLE user (
userid SERIAL PRIMARY KEY,
username VARCHAR(16) UNIQUE NOT NULL
)

This will create userid as auto-increment primary key indexed. If you don't want this as primary key, just remove PRIMARY KEY.

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Use a column of type SERIAL. It works the same way as AUTOINCREMEMT on some other DBs. (Check the docs for other features you can use with it.)

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With current Postgres, you can just use SERIAL for the column type.

With older versions of Postgres, you can implement this using SEQUENCE; the relevant procedure is:

CREATE SEQUENCE mytable_myid_seq;
ALTER TABLE mytable ALTER COLUMN myid SET DEFAULT NEXTVAL('mytable_myid_seq');

A good article on this is MySQL versus PostgreSQL: Adding an Auto-Increment Column to a Table