Job Ready SQL

Introduction

Modern computer applications rely heavily on databases, even when the program in question isn't designed to help users manage data. Computer games rely on databases to keep track of characters, character attributes, items that each character can use during gameplay, and even locations within the game. A learning management system (LMS) uses databases to keep track of learners, instructors, content, grades, attendance, and communication between users.

A database can contain data that is structured or unstructured. Modern database software programs hosting databases can usually handle both structured and unstructured data, but it is still good to understand the difference.

In a database with structured data, which we will call a structured database, the data is organized in a specific pattern. This makes it easy to control what data is available and where to find specific pieces of data. In a structured database, the developer can limit what kinds of data are stored in the database to improve data integrity and reduce the amount of redundant data. This comes as a trade‐off in that creating new data and accessing stored data are relatively slow compared to creating and accessing data in an unstructured database. Structured databases are best for datasets that contain predictable types of data, such as bank accounts, personnel records, and inventories.

Relational databases are highly structured in that they organize data into one or more tables or relations, where ...