Oracle - SQL Table Basics
The mechanics of creating a table are relatively straight forward. Being able to design a well thought out database that will scale to meet the needs of a large scale enterprise is a very challenging undertaking. In these examples we will be working through development of a fairly simple three table database. In doing so we will get to cover a good deal of the development basics for creating tables and indexes.
Creating the person table
CREATE TABLE PERSON ( NUM NUMBER NOT NULL , FIRSTNAME VARCHAR2(20) NULL , GENDER_CODE CHAR(1) NULL , BIRTH_DTTM DATE NULL , INACTIVE_DATE DATE NULL , LASTNAME VARCHAR2(30) NULL , CONSTRAINT PK_PERSON PRIMARY KEY (NUM) ) NOCACHE LOGGING /
Creating the phone table
CREATE TABLE PHONE ( PERSON_NUM NUMBER NOT NULL , TYPE_CODE CHAR(3) NOT NULL , AREA_CODE CHAR(3) NULL , EXCHANGE CHAR(3) NULL , EXTENSION CHAR(4) NULL , CONSTRAINT PK_PHONE PRIMARY KEY (PERSON_NUM, TYPE_CODE) ) NOCACHE LOGGING /
Creating the address table
CREATE TABLE ADDRESS ( PERSON_NUM NUMBER NOT NULL , TYPE_CODE CHAR(4) NOT NULL , STREET1 CHAR(30) NULL , STREET2 CHAR(30) NULL , CITY CHAR(30) NULL , STATE CHAR(2) NULL , POSTAL_CODE CHAR(10) NULL , CONSTRAINT PK_ADDRESS PRIMARY KEY (PERSON_NUM, TYPE_CODE) ) NOCACHE LOGGING /
It is possible, though not advised to create a table without a primary key. I will discuss primary keys on a different page yet to be created. It is also possible to set initial default values for a column though none of the columns in our tables were suitable candidates to do this. There are many good primers on creating tables and databases. The purpose of this page is just to show the basic Oracle syntax by example for creating a table. Also, taking the create table for an existing table and using it as a model is also a very good practice and means of learning.