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SQL Basics
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Course Content

SQL Basics

SQL Basics

1. Selecting
The very first meet with the databaseSELECTing certain columnsLIMITing resultsUnique values from columnUnique values from multiple columnsHow many?How many unique?AliasesTables aliases
2. Filtering
Word filteringNumber filteringCombining conditionsFiltering by numeric intervalMultiple filtering on one columnLIKE filteringNOT like this!
3. Aggregating
MINimal and MAXimal valuesSUMming valuesMean valuesROUNDing
4. Sorting
Sorting by one columnSorting in DESCending orderThe cheapest carSorting by multiple columns
5. Grouping
What is grouping?More aggregate statistics!Grouping by multiple columnsThe cheapest combinationHAVING some conditionsLeast consuming carsFiltering group size
6. Practicing
Challenge: Unique combinationsChallenge: Average Q-series cars priceChallenge: The cheapest new A-series carsChallenge: Relation between engine size and fuel consumptionChallenge: Mileage and manufacture year - is there relation?Challenge: Average price for each model and yearChallenge: The most expensive transmission + engine size combinations

bookLIMITing results

As you might notice, our database is quite large - about three thousand cars. Sometimes we need to limit our results so only a few rows will be displayed. It may be useful if we work with big data and want to check if our query is valid or when we want to find TOP-n observation based on some condition.

To limit the number of rows to be shown use the LIMIT n statement. For example,


              
123

            
SELECT column1, column2
FROM table_name
LIMIT 5
copy

this query will return the first 5 rows from table_name

Task

From the audi_cars table extract the first 10 rows of model, price, mileage columns.

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!

Section 1. Chapter 3
toggle bottom row

bookLIMITing results

As you might notice, our database is quite large - about three thousand cars. Sometimes we need to limit our results so only a few rows will be displayed. It may be useful if we work with big data and want to check if our query is valid or when we want to find TOP-n observation based on some condition.

To limit the number of rows to be shown use the LIMIT n statement. For example,


              
123

            
SELECT column1, column2
FROM table_name
LIMIT 5
copy

this query will return the first 5 rows from table_name

Task

From the audi_cars table extract the first 10 rows of model, price, mileage columns.

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!

Section 1. Chapter 3
toggle bottom row

bookLIMITing results

As you might notice, our database is quite large - about three thousand cars. Sometimes we need to limit our results so only a few rows will be displayed. It may be useful if we work with big data and want to check if our query is valid or when we want to find TOP-n observation based on some condition.

To limit the number of rows to be shown use the LIMIT n statement. For example,


              
123

            
SELECT column1, column2
FROM table_name
LIMIT 5
copy

this query will return the first 5 rows from table_name

Task

From the audi_cars table extract the first 10 rows of model, price, mileage columns.

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!

As you might notice, our database is quite large - about three thousand cars. Sometimes we need to limit our results so only a few rows will be displayed. It may be useful if we work with big data and want to check if our query is valid or when we want to find TOP-n observation based on some condition.

To limit the number of rows to be shown use the LIMIT n statement. For example,


              
123

            
SELECT column1, column2
FROM table_name
LIMIT 5
copy

this query will return the first 5 rows from table_name

Task

From the audi_cars table extract the first 10 rows of model, price, mileage columns.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 1. Chapter 3
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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