SQL - MySQL for Data Analytics and Business Intelligence

Why study SQL?

Whether you are working in Business Intelligence (BI), data science, database administration, or back-end development, you will have to retrieve information from a server storing large amounts of data. To achieve this, you’ll need SQL.

Why did we choose MySQL and not some other relational database management system?

Because it is:

• reliable
• mature
• open-source

You will be much faster in learning and writing efficient queries if you go through a brief introduction to databases. It is the best thing to begin with, so in this video we will discover terms like:

• record
• field
• data table
• data entity
• database
• relation
• and much more.

Although with some procedural elements, SQL is mainly regarded as a declarative programming language, it is nonprocedural. This means, while coding, you will not be interested in how you want the job done. The focus is on what result you want to obtain.

The Data Definition Language, DDL, is called a language, but you can think of it as a syntax, a set of statements that allow the user to define or modify data structures and objects, such as tables. Examples of the statements of the Data Definition Language are:

• CREATE
• ALTER
• RENAME
• TRUNCATE

A brief explanation on what SQL keywords are about.

We will learn about some DML statements that allow us to manipulate the data in the tables of a database:

• SELECT
• INSERT
• UPDATE
• DELETE

The Data Control Language is a syntax containing only two statements – GRANT and REVOKE. These statements allow us to manage the rights users have in a database.

A brief introduction the Transaction Control Language (TCL) and its application.

In this lesson, we will provide you with the tools that are essential for dealing with relational databases. They will help you maintain a database that can be characterized as:

• compact
• well-structured
• efficient

In this lecture, we will focus on the differences between spreadsheets and databases. This exercise will be relevant not only for current Excel users. Those of you who do not use Excel regularly will still have the chance to understand the advantages and the disadvantages of using databases or spreadsheets. 

To complete our theoretical preparation, we will need to learn more database terminology. We will discuss the meaning of such terms as:

• database designer
• entity-relationship diagram
• relational and database schema
• database manipulation, management, and administration

In this video, we will introduce the concept of using primary keys in MySQL.

In this lesson, we will present the concept of using foreign keys in MySQL, as well as their relation to primary keys.

Here, we will explain what unique keys are, and will introduce you to null values in SQL.

This is a lecture in which we will try to illustrate that relationships between tables can be categorized. We will study the main types of relationships you will likely need in your workplace.

A guide for the installation of the MySQL server and MySQL Workbench.

This is a visualization that explains which MySQL features we must install and why.

A brief description of what it means to set up a connection between Workbench and the MySQL Server. 

The focus of this video is getting acquainted with the MySQL Workbench interface.

In this lesson, we will show you how to create your own database, also called schema, starting from scratch.

In this video, we will look at the MySQL Workbench interface in more detail as it can help us manage our database better. 

In this lecture, we will introduce you to the measures that characterize the various data types available in SQL.

The text format in SQL is called string. In this lecture, we will explore a few string data types in SQL.

Numbers are stored in so-called numeric data types. We will go through the most notable types in MySQL – integer, fixed-point, and floating-point data types.

In this lesson, we will compare two numeric data types in SQL – the fixed-point and the floating-point data type. 

In addition to string and numeric data types, SQL allows you to store data that represents a date, time, binary, or list of options, amongst others. In this lesson, we will cover a few noteworthy data types that you will frequently see and work with.

In this lecture, we will take our “first steps” into creating SQL tables. We will study in a bit more detail the rules allowing us to create a table. 

In this video we will explain what the purpose of using queries is. As an example, we will use a query to set a default database.

Here we will share a few notes on using data tables in MySQL.

In this section, we’ll learn how to assign constraints on tables. Our focus in this lesson will be on the primary key constraint.

You know that relationships between the tables in a database are formed through the interaction between primary and foreign keys. We’ll learn how to work with the latter in this lecture.

In this video, we will execute the query we created during the previous lesson, and then we will present a few possible ways to add a foreign key constraint in SQL.

Unique keys ensure that all values in a column (or a set of columns) are different. Just like primary and foreign keys, unique keys are implemented in SQL through a constraint – the Unique constraint.

The DEFAULT constraint helps us assign a default value to every row of a column. In this lecture, we will go through a couple of examples that will best clarify the subject.

The “not null” restriction in MySQL is applied through the NOT NULL constraint. It means that, when you insert values in the table, you cannot leave the respective field empty. And if you leave it empty, MySQL will signal an error.

In this lesson we will explain the differences between the following three elements:

• a NULL value
• a “NONE” response
• the number zero

Throughout the course, we are strictly complying with coding style rules. There are many ways you can write your SQL code, but there are only a few that are considered to be professional.

Here we’ll apply what we learned in the previous lecture in an exercise.

In the remaining part of the course, you’ll be manipulating data in MySQL. To help you achieve this goal, we have re-organized the huge ‘employees’ database script in an SQL file that you can download and run in Workbench. 

The statement you will be using almost all the time is SELECT. It is one of the most important statements in MySQL and SQL. When extracting information, SELECT goes with FROM. You are always selecting something from a certain table or other types of SQL objects.