How to create id with AUTO_INCREMENT on Oracle?

Question

It appears that there is no concept of AUTO_INCREMENT in Oracle, up until and including version 11g.

How can I create a column that behaves like auto increment in Or

Answer 1

SYS_GUID returns a GUID-- a globally unique ID. A SYS_GUID is a RAW(16). It does not generate an incrementing numeric value.

If you want to create an incrementing numeric key, you'll want to create a sequence.

CREATE SEQUENCE name_of_sequence
  START WITH 1
  INCREMENT BY 1
  CACHE 100;

You would then either use that sequence in your INSERT statement

INSERT INTO name_of_table( primary_key_column, <<other columns>> )
  VALUES( name_of_sequence.nextval, <<other values>> );

Or you can define a trigger that automatically populates the primary key value using the sequence

CREATE OR REPLACE TRIGGER trigger_name
  BEFORE INSERT ON table_name
  FOR EACH ROW
BEGIN
  SELECT name_of_sequence.nextval
    INTO :new.primary_key_column
    FROM dual;
END;

If you are using Oracle 11.1 or later, you can simplify the trigger a bit

CREATE OR REPLACE TRIGGER trigger_name
  BEFORE INSERT ON table_name
  FOR EACH ROW
BEGIN
  :new.primary_key_column := name_of_sequence.nextval;
END;

If you really want to use SYS_GUID

CREATE TABLE table_name (
  primary_key_column raw(16) default sys_guid() primary key,
  <<other columns>>
)

Answer 2

Here is complete solution w.r.t exception/error handling for auto increment, this solution is backward compatible and will work on 11g & 12c, specifically if application is in production.

Please replace 'TABLE_NAME' with your appropriate table name

--checking if table already exisits
BEGIN
    EXECUTE IMMEDIATE 'DROP TABLE TABLE_NAME';
    EXCEPTION WHEN OTHERS THEN NULL;
END;
/

--creating table
CREATE TABLE TABLE_NAME (
       ID NUMBER(10) PRIMARY KEY NOT NULL,
       .
       .
       .
);

--checking if sequence already exists
BEGIN
    EXECUTE IMMEDIATE 'DROP SEQUENCE TABLE_NAME_SEQ';
    EXCEPTION WHEN OTHERS THEN NULL;
END;

--creating sequence
/
CREATE SEQUENCE TABLE_NAME_SEQ START WITH 1 INCREMENT BY 1 MINVALUE 1 NOMAXVALUE NOCYCLE CACHE 2;

--granting rights as per required user group
/
GRANT SELECT, INSERT, UPDATE, DELETE ON TABLE_NAME TO USER_GROUP;

-- creating trigger
/
CREATE OR REPLACE TRIGGER TABLE_NAME_TS BEFORE INSERT OR UPDATE ON TABLE_NAME FOR EACH ROW
BEGIN    
    -- auto increment column
    SELECT TABLE_NAME_SEQ.NextVal INTO :New.ID FROM dual;

    -- You can also put some other required default data as per need of your columns, for example
    SELECT SYS_CONTEXT('USERENV', 'SESSIONID') INTO :New.SessionID FROM dual;
    SELECT SYS_CONTEXT('USERENV','SERVER_HOST') INTO :New.HostName FROM dual;
    SELECT SYS_CONTEXT('USERENV','OS_USER') INTO :New.LoginID FROM dual;    
    .
    .
    .
END;
/

Answer 3

oracle has sequences AND identity columns in 12c

http://www.oracle-base.com/articles/12c/identity-columns-in-oracle-12cr1.php#identity-columns

I found this but not sure what rdb 7 is http://www.oracle.com/technetwork/products/rdb/0307-identity-columns-128126.pdf

Answer 4

FUNCTION GETUNIQUEID_2 RETURN VARCHAR2
AS
v_curr_id NUMBER;
v_inc NUMBER;
v_next_val NUMBER;
pragma autonomous_transaction;
begin 
CREATE SEQUENCE sequnce
START WITH YYMMDD0000000001
INCREMENT BY 1
NOCACHE
select sequence.nextval into v_curr_id from dual;
if(substr(v_curr_id,0,6)= to_char(sysdate,'yymmdd')) then
v_next_val := to_number(to_char(SYSDATE+1, 'yymmdd') || '0000000000');
v_inc := v_next_val - v_curr_id;
execute immediate ' alter sequence sequence increment by ' || v_inc ;
select sequence.nextval into v_curr_id from dual;
execute immediate ' alter sequence sequence increment by 1';
else
dbms_output.put_line('exception : file not found');
end if;
RETURN 'ID'||v_curr_id;
END;