Sequences of Oracle

It turns out that Oracle is only used, because there is no auto-incrementing column (like MSSQL), so a method called "Automatic Acquisition" is adopted.
Today, I finally learned this sequence. It is similar to the "auto-collect" method. It is like a table. As long as the value is included in it, it can automatically increase by step.

Create:
Create sequence test_sequence
Increment by 1 -- data added each time
Start with 1 -- count from 1
Nomaxvalue -- do not set the maximum value
Nocycle -- always accumulate without repeating
Cache 10;

Two Methods of getting the number: 1. nextval: get the next one, and return the result after increasing
2. currval: Get the current value without increasing

It can be applied directly in SQL statements:
Select test_sequence.currval from dual

 

I feel quite fresh, smiling at me