Oracle Create primary key self-increment table

Introduction

This article focuses on the use of sequences in Oracle if you create a self-growth table.

Create Tabletb_student (ID Number(Ten) not NULL, Createtime DATE not NULL,   constraintPk_tb_studentPrimary Key(ID)); Comment on Table"Tb_student" is' StudentTable'; Comment on column"Tb_student". " Id is'primary Key ID'; Comment on column"Tb_student". " Createtime " is'creation Time';--Create a sequenceCreatesequence Seq_tb_studentminvalue1Nomaxvaluestart with 1Increment by 1nocycle--keep accumulating, not loopingNoCache; --Create a trigger if the INSERT statement does not specify an ID to automatically insert the growth valueCREATE OR REPLACE TRIGGERTr_tb_student beforeINSERT  onTb_student forEach ROW when(new.id is NULL)beginSelectSeq_tb_student.nextval into: new.id fromdual;End;

NOTE: Triggers are non-mandatory, and you can specify the insertion value from a business requirement.

Summary

Note Oracle restricts the object name to a character length of 30 characters, so the table name must be controlled at a certain length otherwise the creation sequence may exceed the limit, and it is recommended that the table name be controlled below 27 characters.

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Oracle Create primary key self-increment table