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Introduction to SQL
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Kurssisisältö

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
The COUNT() Function

COUNT() is a function that allows you to count rows in a table or count how many rows match certain criteria.

Let’s see an example:


              
12

            
SELECT COUNT(name) 
FROM country;
copy

To count the total number of rows in the table, we can use the following syntax:


              
12

            
SELECT COUNT(*)
FROM country;
copy

Here is the country table we are working with:

Tehtävä

Swipe to start coding

Write an SQL query to retrieve the number of rows from the country table where the continent is 'Asia' with a population of over 1000000.

Ratkaisu

Switch to desktopVaihda työpöytään todellista harjoitusta vartenJatka siitä, missä olet käyttämällä jotakin alla olevista vaihtoehdoista
Oliko kaikki selvää?

Miten voimme parantaa sitä?

Kiitos palautteestasi!

Osio 5. Luku 3
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book
The COUNT() Function

COUNT() is a function that allows you to count rows in a table or count how many rows match certain criteria.

Let’s see an example:


              
12

            
SELECT COUNT(name) 
FROM country;
copy

To count the total number of rows in the table, we can use the following syntax:


              
12

            
SELECT COUNT(*)
FROM country;
copy

Here is the country table we are working with:

Tehtävä

Swipe to start coding

Write an SQL query to retrieve the number of rows from the country table where the continent is 'Asia' with a population of over 1000000.

Ratkaisu

Switch to desktopVaihda työpöytään todellista harjoitusta vartenJatka siitä, missä olet käyttämällä jotakin alla olevista vaihtoehdoista
Oliko kaikki selvää?

Miten voimme parantaa sitä?

Kiitos palautteestasi!

Osio 5. Luku 3
Switch to desktopVaihda työpöytään todellista harjoitusta vartenJatka siitä, missä olet käyttämällä jotakin alla olevista vaihtoehdoista
Pahoittelemme, että jotain meni pieleen. Mitä tapahtui?
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