Course Content

Introduction to SQL

1. Retrieving Data

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

2. Sorting Retrieved Data

Sorting Data Challenge: Population Sort Sorting by Multiple Columns Challenge: Dual-Sort Query 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

3. Filtering Data

Using the WHERE Clause Challenge: North America Population Sort The WHERE Clause Operators Challenge: Population Threshold Query Checking for a Range of Values Checking for NO Value

4. Advanced Data Filtering

Using the AND Operator Challenge: Europe Region Sort Using the OR operator Challenge: America Regions Filter Using the NOT Operator Challenge: Non-Europe Capitals Sort

5. Aggregate Functions

The AVG() Function Challenge: Surface Area Selection The COUNT() Function Challenge: Continental Count The MAX() Function The MIN() Function Challenge: Large Surface Area Average The SUM() Function

Checking for NO Value

If a column doesn't contain any data, it's considered NULL. To determine if a value is NULL, you don’t just check for equality. Instead, you use the WHERE clause with IS NULL in a SELECT statement to find rows where the column’s value is NULL.

The syntax for it looks like this:

Let's illustrate this with an example:


              123
            
SELECT name
FROM country
WHERE region IS NULL;

Here is the country table we are working with:

Task

Swipe to show code editor

Write an SQL query that returns the name and capital columns with no population.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 6

Checking for NO Value

The syntax for it looks like this:

Let's illustrate this with an example:


              123
            
SELECT name
FROM country
WHERE region IS NULL;

Here is the country table we are working with:

Task

Swipe to show code editor

Write an SQL query that returns the name and capital columns with no population.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 6

Checking for NO Value

The syntax for it looks like this:

Let's illustrate this with an example:


              123
            
SELECT name
FROM country
WHERE region IS NULL;

Here is the country table we are working with:

Task

Swipe to show code editor

Write an SQL query that returns the name and capital columns with no population.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

The syntax for it looks like this:

Let's illustrate this with an example:


              123
            
SELECT name
FROM country
WHERE region IS NULL;

Here is the country table we are working with:

Task

Swipe to show code editor

Write an SQL query that returns the name and capital columns with no population.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Section 3. Chapter 6

Switch to desktop for real-world practiceContinue from where you are using one of the options below