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SQL Basics
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Зміст курсу

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

bookGrouping by multiple columns

Can we group observations based on multiple columns? For example, we can group all cars by year and engine size and find the most expensive within these.

To group by multiple columns use the same approach as for sorting by multiple columns: just put it within GROUP BY statement separated with a comma. The query for the example above will look like this:


              
123

            
SELECT year, enginesize, AVG(price)
FROM audi_cars
GROUP BY year, enginesize
copy

Завдання

From the audi_cars table calculate the maximum, average, and minimum price for each model manufactured in different years.

Switch to desktopПерейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів
Все було зрозуміло?

Як ми можемо покращити це?

Дякуємо за ваш відгук!

Секція 5. Розділ 3
toggle bottom row

bookGrouping by multiple columns

Can we group observations based on multiple columns? For example, we can group all cars by year and engine size and find the most expensive within these.

To group by multiple columns use the same approach as for sorting by multiple columns: just put it within GROUP BY statement separated with a comma. The query for the example above will look like this:


              
123

            
SELECT year, enginesize, AVG(price)
FROM audi_cars
GROUP BY year, enginesize
copy

Завдання

From the audi_cars table calculate the maximum, average, and minimum price for each model manufactured in different years.

Switch to desktopПерейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів
Все було зрозуміло?

Як ми можемо покращити це?

Дякуємо за ваш відгук!

Секція 5. Розділ 3
toggle bottom row

bookGrouping by multiple columns

Can we group observations based on multiple columns? For example, we can group all cars by year and engine size and find the most expensive within these.

To group by multiple columns use the same approach as for sorting by multiple columns: just put it within GROUP BY statement separated with a comma. The query for the example above will look like this:


              
123

            
SELECT year, enginesize, AVG(price)
FROM audi_cars
GROUP BY year, enginesize
copy

Завдання

From the audi_cars table calculate the maximum, average, and minimum price for each model manufactured in different years.

Switch to desktopПерейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів
Все було зрозуміло?

Як ми можемо покращити це?

Дякуємо за ваш відгук!

Can we group observations based on multiple columns? For example, we can group all cars by year and engine size and find the most expensive within these.

To group by multiple columns use the same approach as for sorting by multiple columns: just put it within GROUP BY statement separated with a comma. The query for the example above will look like this:


              
123

            
SELECT year, enginesize, AVG(price)
FROM audi_cars
GROUP BY year, enginesize
copy

Завдання

From the audi_cars table calculate the maximum, average, and minimum price for each model manufactured in different years.

Switch to desktopПерейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів
Секція 5. Розділ 3
Switch to desktopПерейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів
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