Job Ready SQL

Lesson 6Diving into SQL

SQL is designed as a universal language to manage data stored in a relational database management system. In this lesson, we will look at some of the features of SQL before jumping into using it heavily to manage data. This includes the topic of working with null values and how to use them in MySQL. We will also take a look at indexing.

Learning Objectives

By the end of this lesson, you will be able to:

• Discuss the origins of SQL
• Demonstrate syntax features of core SQL, including the use of letter case, spaces, quotation marks, and semicolons
• Explain what a null value is in a dataset
• Add null values to a table
• Explain how relational databases use indexes to improve retrieval efficiency
• Identify design features that can affect indexes

INTRODUCTION TO SQL

SQL stands for Structured Query Language, and it can be pronounced like “sequel” or using the letters S‐Q‐L. It is designed to work with any relational database management system (RDBMS), which includes MySQL Server, Microsoft SQL Server, and Oracle Database, among others. Because it works universally across RDBMSs, programming languages such as Java, C#, and PHP support the use of SQL to retrieve and manage data stored in an RDBMS.

As relational database systems have become more prominent and widespread, RDBMS‐specific versions of SQL have been developed to extend its abilities and improve performance within those systems. As an example, Microsoft SQL Server uses a variation named Transact‐SQL ...