Oracle uses triggers to implement auto-increment columns, and oracle uses triggers

Oracle uses triggers to implement auto-increment columns, and oracle uses triggers

Oracle uses triggers to implement auto-increment Columns

 

Oracle does not have the auto-increment function. mysql and sqlserver use auto_increment and identity () to implement auto-increment respectively. Oracle can only be implemented through sequences. During each insertion, it is inconvenient to display the sequence value to the auto-increment column. The trigger is used here, in this way, the three databases are syntactically consistent during insertion, facilitating DAO code porting. The following is an ORACLE implementation example. The steps are as follows:

1. Create a table

Create tabletest_user (

User_id number (10, 0) primary key,

User_name varchar2 (40)

);

 

2. Create a sequence

Create sequencetest_user_seq start with 1 maxvalue 9999999999 increment by 1;

 

3. Create a trigger

Create or replace

Triggertest_user_trigger

Before insert ontest_user

For each row

Begin

Selecttest_user_seq.nextval into: new. user_id from dual;

End;

4. insert data

Insert into test_user (user_name) values ('Tom ');

Insert into test_user (user_name) values ('jack ');

 

5. Test Results

 

Select * from test_user;