Introduction to SQL



Author: Alina Myronets

Course description

This course is for you if you are new to SQL, you want to quickly learn how to get the most out of SQL and you want to learn how to use SQL in your own application development.


Complete all chapters to get certificate


Retrieving Data


In this section, we will learn how to use the SQL SELECT statement to get a single table column, multiple table columns, and all table columns. We will also find out how to return unique values.

Retrieving Individual Columns

Retrieving Multiple Columns

Retrieving All Columns

Retrieving Distinct Rows

Limiting Results

Challenge: Find the Population of the Countries

Challenge: Find All Countries

Challenge: Find All Countries With Their IDs

Challenge: Find Country Capitals

Challenge: Find the Regions in Which All Countries Are Located

Sorting Retrieved Data


In this section, we will learn how to sort retrieved data using the ORDER BY clause. This clause, which must be the last in the SELECT statement, can be used to sort data on one or more columns as needed.

Sorting Data


Sorting by Multiple Columns


Specifying Sort Direction

Challenge: Sort the Countries by Region and Capital

Challenge: Sort Capitals in Descending Order

Challenge: Sort Countries in Ascending Order

Challenge: Find Countries, Their IDs, and Their Populations

Challenge: Find Countries, IDs, Populations, Regions, and Sort Them

Challenge: Find All Continents and Sort Them in Ascending Order

Filtering Data


In this section, we will learn how to filter returned data using the SELECT statement’s WHERE clause. We will learn how to test for equality, inequality, more and less significant than value ranges, and NULL values.

Using the WHERE Clause


The WHERE Clause Operators


Checking for a Range of Values

Checking for NO Value

Advanced Data Filtering


In this section, we will learn how to combine WHERE clauses with the AND and OR operators. We will also find out how the NOT operator works.

Using the AND Operator


Using the OR operator


Using the NOT Operator


Aggregate Functions


In this section, we will learn what the SQL aggregate functions are and how to use them to summarize table data.

The AVG() Function


The COUNT() Function


The MAX() Function

The MIN() Function


The SUM() Function