Oracle primary key auto-Increment

Set the primary key and auto-increment the primary key in the Oracle table. Because Oracle cannot directly set the auto-increment number, you can only write sequence and add a trigger on your own;

After searching for a while on the network, I found that all of them were forwarded by blog posts. I wrote it according to their steps, but there was a problem. It was estimated that my own capabilities were limited. Many Masters did not dare to compliment me, I wrote it myself. The following is the step, only the auto-Increment Function of the Oracle primary key. The ORACLE trigger is very deep. I haven't sunk it yet. Please let me know at a high level ......

First create a table: Dept

Create Table dept (deptno number (10), deptname
Varchar2 (20), deptdescript varchar2 (20 ))

In this dept, deptno is the primary key;

The sequence is created below;

Create sequence dept_sequence
Increment by 1 start with 1 nomaxvalue nocycle Cache 10;

The following is a trigger. when data is inserted into a table, auto-increment of the primary key is triggered;
Create or replace trigger dept_trigger
Before insert on dept for each row
Begin select dept_sequence.nextval
Into: New. deptno from dual; end;

The sequence of my own table is marked with the color above, and the name of the trigger added by myself; it is not difficult to understand it;

Add the primary and foreign key references of the two tables: deptno is the primary key in Dept, and depment is the foreign key in EMP.

Alter table emp add constraint fr_key foreign key (depment)
References dept (deptno );