Зміст курсу

SQL Basics

1. Selecting

The very first meet with the database SELECTing certain columns LIMITing results Unique values from column Unique values from multiple columns How many?How many unique?Aliases Tables aliases

2. Filtering

Word filtering Number filtering Combining conditions Filtering by numeric interval Multiple filtering on one column LIKE filtering NOT like this!

3. Aggregating

MINimal and MAXimal values SUMming values Mean values ROUNDing

4. Sorting

Sorting by one column Sorting in DESCending order The cheapest car Sorting by multiple columns

5. Grouping

What is grouping?More aggregate statistics!Grouping by multiple columns The cheapest combination HAVING some conditions Least consuming cars Filtering group size

6. Practicing

Challenge: Unique combinations Challenge: Average Q-series cars price Challenge: The cheapest new A-series cars Challenge: Relation between engine size and fuel consumption Challenge: Mileage and manufacture year - is there relation?Challenge: Average price for each model and year Challenge: The most expensive transmission + engine size combinations

What is grouping?

Grouping - is arranging observations into sub-groups based on unique values in some column. For example, we can group our audi_cars table by transmission column (contains 3 unique values). There will be observations within each subgroup. So, what's the point of grouping?

In SQL grouping is often used in pair with some aggregate function within SELECT. For example, we can calculate the average price for each transmission type.


              123
            
SELECT AVG(price), transmission
FROM audi_cars
GROUP BY transmission

This will return all the transmissions types with average prices within each group.

Завдання

From the audi_cars table calculate the average price of each model. Round price to two decimals.

Завдання

From the audi_cars table calculate the average price of each model. Round price to two decimals.

Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів

Все було зрозуміло?

Секція 5. Розділ 1

What is grouping?

In SQL grouping is often used in pair with some aggregate function within SELECT. For example, we can calculate the average price for each transmission type.


              123
            
SELECT AVG(price), transmission
FROM audi_cars
GROUP BY transmission

This will return all the transmissions types with average prices within each group.

Завдання

From the audi_cars table calculate the average price of each model. Round price to two decimals.

Завдання

From the audi_cars table calculate the average price of each model. Round price to two decimals.

Все було зрозуміло?

Секція 5. Розділ 1

What is grouping?

In SQL grouping is often used in pair with some aggregate function within SELECT. For example, we can calculate the average price for each transmission type.


              123
            
SELECT AVG(price), transmission
FROM audi_cars
GROUP BY transmission

This will return all the transmissions types with average prices within each group.

Завдання

From the audi_cars table calculate the average price of each model. Round price to two decimals.

Завдання

From the audi_cars table calculate the average price of each model. Round price to two decimals.

Все було зрозуміло?

In SQL grouping is often used in pair with some aggregate function within SELECT. For example, we can calculate the average price for each transmission type.


              123
            
SELECT AVG(price), transmission
FROM audi_cars
GROUP BY transmission

This will return all the transmissions types with average prices within each group.

Завдання

From the audi_cars table calculate the average price of each model. Round price to two decimals.

Секція 5. Розділ 1