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Introduction to SQL
course content

Course Content

Introduction to SQL

Introduction to SQL

1. Retrieving Data
Retrieving Individual ColumnsRetrieving Multiple Columns Retrieving All ColumnsRetrieving Distinct RowsLimiting ResultsChallenge: Find the Population of the CountriesChallenge: Find All CountriesChallenge: Find All Countries With Their IDsChallenge: Find Country CapitalsChallenge: Find the Regions in Which All Countries Are Located
2. Sorting Retrieved Data
Sorting DataChallenge: Population SortSorting by Multiple ColumnsChallenge: Dual-Sort QuerySpecifying Sort DirectionChallenge: Sort the Countries by Region and CapitalChallenge: Sort Capitals in Descending OrderChallenge: Sort Countries in Ascending OrderChallenge: Find Countries, Their IDs, and Their PopulationsChallenge: Find Countries, IDs, Populations, Regions, and Sort ThemChallenge: Find All Continents and Sort Them in Ascending Order
3. Filtering Data
Using the WHERE ClauseChallenge: North America Population SortThe WHERE Clause Operators Challenge: Population Threshold QueryChecking for a Range of ValuesChecking for NO Value
4. Advanced Data Filtering
Using the AND OperatorChallenge: Europe Region SortUsing the OR operatorChallenge: America Regions FilterUsing the NOT OperatorChallenge: Non-Europe Capitals Sort
5. Aggregate Functions
The AVG() FunctionChallenge: Surface Area SelectionThe COUNT() FunctionChallenge: Continental CountThe MAX() FunctionThe MIN() FunctionChallenge: Large Surface Area AverageThe SUM() Function

book
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:

sql

Let's illustrate this with an example:


              
123

            
SELECT name
FROM country
WHERE region IS NULL;
copy

Here is the country table we are working with:

Task

Swipe to start coding

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

Solution

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SectionΒ 3. ChapterΒ 6
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book
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:

sql

Let's illustrate this with an example:


              
123

            
SELECT name
FROM country
WHERE region IS NULL;
copy

Here is the country table we are working with:

Task

Swipe to start coding

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

Solution

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 3. ChapterΒ 6
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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