Database Tutorial

This database tutorial is for beginners. It explains basic concepts and assumes no prior knowledge of databases.

You don’t need to follow along – there aren’t any exercises. But there are plenty of screenshots and a few diagrams. The purpose of the tutorial is to introduce you to the basic concepts of databases.

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What is an ORDBMS?

ORDBMS stands for Object-Relational Database Management System.

An ORDBMS is a database management system that is a hybrid between the object-oriented model (OODBMS) and the relational model (RDBMS).

Each of those two models has their strengths and weaknesses. By combining the two models, a DBMS can take advantage of various strengths from each model.

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What is an OODBMS?

OODBMS stands for Object-Oriented Database Management System.

An object-oriented database management system (also known simply as an object database) is a DBMS where data is represented in the form of objects, as used in object-oriented programming.

In contrast to relational database management systems (RDBMSs), where data is stored in tables with rows and columns, an object-oriented database stores complex data and relationships between data directly, without mapping to relational rows and columns.

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What is a Data Warehouse?

A data warehouse is a large collection of data that can be used to help an organisation make key business decisions.

Here’s a more precise definition of the term,  as coined by Bill Inmon, (considered by many to be “the father of data warehousing”):

A data warehouse is a subject-oriented, integrated, nonvolatile, and time-variant collection of data in support of management’s decisions.

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What is Big Data?

The term big data refers to the massive amounts of data – both structured and unstructured – that inundate organisations on a day-to-day basis.

Typically, big data is so large, and accumulates so fast, that traditional data storage and processing applications are inadequate.

The big data industry helps organisations capture and analyse their big data, so that those organisations can make more informed business decisions.

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What is a DBMS?

DBMS stands for Database Management System.

A database management system is an application that enables the creation and administration of databases. Database management system is a broad term that includes any system that performs that function.

The most common type of DBMS is an RDBMS (Relational Database Management System). RDBMSs allow you to create relational databases – databases that have multiple tables that contain related data.

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What is a Database Schema?

In database terms, a schema (pronounced “skee-muh” or “skee-mah”) is the organisation and structure of a database. Both schemas and schemata can be used as plural forms.

A schema contains schema objects, which could be tablescolumns, data types, views, stored procedures, relationships, primary keys, foreign keys, etc.

A database schema can be represented in a visual diagram, which shows the database objects and their relationship with each other.

Screenshot of a database schema.
A basic schema diagram representing a small three-table database.

Above is a simple example of a schema diagram. It shows three tables, along with their data types, relationships between the tables, as well as their primary keys and foreign keys.

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What is an Orphaned Record?

An orphaned record is a record whose foreign key value references a non-existent primary key value.

Orphaned records are a concept within database relationships. If a record in a related table references a non-existent record in the primary table, it is said to be an orphaned record. This is because it has no “parent” with which its data is associated with.

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