Course Content

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

Grouping 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

Task

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

Task

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

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Section 5. Chapter 3

Grouping 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.


              123
            
SELECT year, enginesize, AVG(price)
FROM audi_cars
GROUP BY year, enginesize

Task

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

Task

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

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Section 5. Chapter 3

Grouping 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.


              123
            
SELECT year, enginesize, AVG(price)
FROM audi_cars
GROUP BY year, enginesize

Task

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

Task

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

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

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.


              123
            
SELECT year, enginesize, AVG(price)
FROM audi_cars
GROUP BY year, enginesize

Task

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

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Section 5. Chapter 3

Switch to desktop for real-world practiceContinue from where you are using one of the options below