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Introduction to SQL
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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
Limiting Results

We know that the SELECT operator can retrieve all rows from a table of all or the specific columns. However, what if we only need to fetch a specific number of rows?

We can do it using the LIMIT clause. It is always used at the end of the query. Here is the syntax for it:

sql

In the example below, we extract the first 7 rows (in our case, the capitals of the countries) from the column:


              
123

            
SELECT capital 
FROM country 
LIMIT 7;
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Here's a short example of the country table:

Task

Swipe to start coding

Write an SQL query to retrieve 3 distinct continent values from the country table.

Solution

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SectionΒ 1. ChapterΒ 5
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book
Limiting Results

We know that the SELECT operator can retrieve all rows from a table of all or the specific columns. However, what if we only need to fetch a specific number of rows?

We can do it using the LIMIT clause. It is always used at the end of the query. Here is the syntax for it:

sql

In the example below, we extract the first 7 rows (in our case, the capitals of the countries) from the column:


              
123

            
SELECT capital 
FROM country 
LIMIT 7;
copy

Here's a short example of the country table:

Task

Swipe to start coding

Write an SQL query to retrieve 3 distinct continent values from the country table.

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 1. ChapterΒ 5
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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