Oracle self-Increment column creation method

Oracle does not have functionality such as a self-increment field, but it can be implemented through triggers (trigger) and sequences (sequence).

Build a test table first:

CREATE TABLE Userlogin
(

ID Number (6) is not NULL,

Name VARCHAR2 (+) NOT NULL primary key

)

Tablespace users

/

First step: Create sequence

Create sequence Userlogin_seq increment by 1 start with 1 minvalue 1 maxvalue 9999999999999 nocache order;

Step two: Create a before insert trigger based on the table, using the sequence you just created in the trigger

Create or Replace Trigger Userlogin_trigger
Before insert on Userlogin
For each row
Begin
Select Userlogin_seq.nextval into:new.id from Sys.dual;
End

/

Step three: Test in the Userlogin table

Write an INSERT statement, insert a record, see the ID field has been increased since the increase is OK.