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History of the Database

Objectives – History of the Database

This article covers the following objectives about the history of the database:

  • Describe the evolution of the database and give an example of its role in the business world
  • Name important historical contributions in database development and design
  • List and explain the three major steps in the database development process

Database technology and its uses are not static. Today’s databases are very different from those of 20 years ago. Future databases will be different again.

Purpose

  • History provides perspective for where we are today in information technology.
  • The next time you use your computer, your video gaming system, or your smart phone, you will realize how far we’ve come to get to this point and what events brought us here.
  • Data Modeling is the first step in database development.
  • This lesson includes an overview of the content that is covered in the remainder of the course.

History of the Database: Timeline

  • In the 60’s, computer machines became cost effective for companies.
  • Early 70’s, the relational model for databases was proposed.
  • In 1976, the entity relationship model (ERM) for database design was proposed.
  • Early 1980’s, the first commercially-available relational database systems start to appear at the beginning of the 1980’s with Oracle.
  • A few years after, the SQL (structured query language) became “intergalactic standard.“
  • Early 90’s, an industry shakeout began with fewer surviving companies.
  • Mid-1990’s: The usable Internet is finally here.
  • Early 21st century, there was a big growth of database applications that is continuing till today.

Non-relational databases, including hierarchical databases such as IBM’s IMS, preceded relational databases. And some of them are still in use today. This history focuses only on relational databases, which are easily the most widely used today because of their flexibility and relative ease of use.

What Does Data Modeling Have to do with a Database?

  • Data modeling is the first step in the database development process.
  • It involves collecting and analyzing the data that a business needs to track, and then diagramming the organization of that data in an Entity Relationship Diagram.
Data Modeling

Database Development Process

  • Data modeling begins by researching the information requirements of a business.
  • Example: Here is a set of information requirements.
    • I am on top of the HR Dept. for a private company. We actually require to have all the data of each employee stored. We need to track the basic employees’ information. Every employee should have a unique number.
  • Example: Here is a set of information requirements.
    • The company I work at has several departments. Every employee belongs to a Dept. We need to know the dept responsible for each employee and the dept location. Each dept. has a unique number.
    • Some of the employees are part of the management team. We need to know each employee’s manager and all of the employees that are managed by each manager.
  • An entity relationship diagram should completely capture and accurately model the organization’s information needs and support the functions of the business.
  • Example: The following entity relationship diagram represents the information requirements of the Human Resources Department.
Database Development Process

This is exactly what you will learn in the Data Modeling tutorial. You will be able to transform business requirements into data models called Entity Relationship Diagrams (ERDs).

  • Step two, the database design phase of the development process, translates the information modeled on the entity relationship diagram to a table instance chart.
Database Development Process

The table instance chart lists the design specifications of the information and has the following components:

  • Table name
  • Column names
  • Keys: a primary key (PK) is the unique identifier for each row of data; a foreign key (FK) links data in one table to the data in a second table by referring to the PK column in the second table
  • Nulls: indicates if a column must contain a value (mandatory)
  • Unique: indicates if the value contained in a column is unique within the table
  • Data type: identifies the definition and format of the data stored in each column
  • Structured Query Language (SQL) commands are used to build the physical structure of the database.

DATABASE BUILD—Step Three

CREATE TABLE departments
(deptno NUMBER(5) CONSTRAINT depts_deptno_PK PRIMARY KEY,
name VARCHAR2(25) CONSTRAINT depts_name_NN NOT NULL,
loc VARCHAR2(30) CONSTRAINT depts_loc_NN NOT NULL);
CREATE TABLE employees
(empno NUMBER(9) CONSTRAINT emps_empno_PK PRIMARY KEY,
fname VARCHAR2(15) CONSTRAINT emps_fname_NN NOT NULL,
lname VARCHAR2(20) CONSTRAINT emps_lname_NN NOT NULL,
hiredate DATE CONSTRAINT emps_hiredt_NN NOT NULL,
salary NUMBER(9,2),
commission NUMBER(9,2),
mgr NUMBER(9) CONSTRAINT emps_mgr_FK
REFERENCES employees(empno),
deptno NUMBER(5) CONSTRAINT emps_deptno_FK
REFERENCES departments(deptno));
  • SQL is also used to populate, access, and manipulate the data within the relational database.

DATABASE BUILD—Step Three

INSERT INTO departments
(deptno,name,loc)
VALUES
(123,'Accounts','US');
SELECT fname, lname, deptno
FROM employees
WHERE deptno = 123;
UPDATE departments
SET name = 'marketing'
WHERE deptno=123

In SQL, you will learn how to make the actual database. Right now, it’s all about understanding what is needed using smart planning and careful design.

Terminology

Key terms used in this tutorial included:

  • Data type
  • Foreign key (FK)
  • Nulls
  • Primary key (PK)
  • Table instance chart
  • Unique

Summary

In this tutorial, you should have learned how to:

  • Describe the evolution of the database and give an example of its role in the business world
  • Name important historical contributions in database development and design
  • List and explain the three major steps in the database development process

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