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

The WHERE Clause Operators

SQL supports a lot of conditional statements.

Let’s look at the examples:
This example lists all countries that have a population of less than 2424200:


              123
            
SELECT name, population
FROM country
WHERE population < 2424200;

The following example retrieves all countries with a population less than or equal to 2424200:


              123
            
SELECT name, population
FROM country
WHERE population <= 2424200;

The following example retrieves all non-Asian countries:


              123
            
SELECT name, continent
FROM country
WHERE continent<>'Asia';

Task

Write an SQL query to retrieve the name, population, region, and capital columns from the country table (please retrieve these columns in this order), returning only the countries with a region named Southern Europe.

Note
Please note that Southern Europe should be correctly capitalized, and southern europe should not be the same. So, be careful and write it as Southern Europe.

Here's a short example of the country table:

id	name	continent	region	surfacearea	capital	population
1	Japan	Asia	Eastern Asia	377829	Tokyo	126714000
2	Latvia	Europe	NULL	64589	Riga	2424200
3	Mexico	North America	Central America	1958201	Mexico City	98881000
...	...	...	...	...	...	...
15	Malta	Europe	Southern Europe	316	Valletta	380200

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Section 3. Chapter 3

The WHERE Clause Operators

SQL supports a lot of conditional statements.

Let’s look at the examples:
This example lists all countries that have a population of less than 2424200:


              123
            
SELECT name, population
FROM country
WHERE population < 2424200;

The following example retrieves all countries with a population less than or equal to 2424200:


              123
            
SELECT name, population
FROM country
WHERE population <= 2424200;

The following example retrieves all non-Asian countries:


              123
            
SELECT name, continent
FROM country
WHERE continent<>'Asia';

Task

Note
Please note that Southern Europe should be correctly capitalized, and southern europe should not be the same. So, be careful and write it as Southern Europe.

Here's a short example of the country table:

id	name	continent	region	surfacearea	capital	population
1	Japan	Asia	Eastern Asia	377829	Tokyo	126714000
2	Latvia	Europe	NULL	64589	Riga	2424200
3	Mexico	North America	Central America	1958201	Mexico City	98881000
...	...	...	...	...	...	...
15	Malta	Europe	Southern Europe	316	Valletta	380200

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 3

The WHERE Clause Operators

SQL supports a lot of conditional statements.

Let’s look at the examples:
This example lists all countries that have a population of less than 2424200:


              123
            
SELECT name, population
FROM country
WHERE population < 2424200;

The following example retrieves all countries with a population less than or equal to 2424200:


              123
            
SELECT name, population
FROM country
WHERE population <= 2424200;

The following example retrieves all non-Asian countries:


              123
            
SELECT name, continent
FROM country
WHERE continent<>'Asia';

Task

Note
Please note that Southern Europe should be correctly capitalized, and southern europe should not be the same. So, be careful and write it as Southern Europe.

Here's a short example of the country table:

id	name	continent	region	surfacearea	capital	population
1	Japan	Asia	Eastern Asia	377829	Tokyo	126714000
2	Latvia	Europe	NULL	64589	Riga	2424200
3	Mexico	North America	Central America	1958201	Mexico City	98881000
...	...	...	...	...	...	...
15	Malta	Europe	Southern Europe	316	Valletta	380200

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

Everything was clear?

Thanks for your feedback!

SQL supports a lot of conditional statements.

Let’s look at the examples:
This example lists all countries that have a population of less than 2424200:


              123
            
SELECT name, population
FROM country
WHERE population < 2424200;

The following example retrieves all countries with a population less than or equal to 2424200:


              123
            
SELECT name, population
FROM country
WHERE population <= 2424200;

The following example retrieves all non-Asian countries:


              123
            
SELECT name, continent
FROM country
WHERE continent<>'Asia';

Task

Note
Please note that Southern Europe should be correctly capitalized, and southern europe should not be the same. So, be careful and write it as Southern Europe.

Here's a short example of the country table:

id	name	continent	region	surfacearea	capital	population
1	Japan	Asia	Eastern Asia	377829	Tokyo	126714000
2	Latvia	Europe	NULL	64589	Riga	2424200
3	Mexico	North America	Central America	1958201	Mexico City	98881000
...	...	...	...	...	...	...
15	Malta	Europe	Southern Europe	316	Valletta	380200

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

Section 3. Chapter 3

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