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

Mean values

The next function we will talk about - is mean. Mean (average) is probably one of the most simple and usable statistics in real life.

For example, for our audi_cars table, we can calculate the average mileage for cars manufactured in 2020. To calculate the average use AVG function followed by column name.


              123
            
SELECT AVG(mileage)
FROM audi_cars
WHERE year = 2020

Task

Using table audi_cars calculate the average price of the A4 model manufactured in 2018.

Task

Using table audi_cars calculate the average price of the A4 model manufactured in 2018.

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

Everything was clear?

Section 3. Chapter 3

Mean values

The next function we will talk about - is mean. Mean (average) is probably one of the most simple and usable statistics in real life.

For example, for our audi_cars table, we can calculate the average mileage for cars manufactured in 2020. To calculate the average use AVG function followed by column name.


              123
            
SELECT AVG(mileage)
FROM audi_cars
WHERE year = 2020

Task

Using table audi_cars calculate the average price of the A4 model manufactured in 2018.

Task

Using table audi_cars calculate the average price of the A4 model manufactured in 2018.

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

Everything was clear?

Section 3. Chapter 3

Mean values

The next function we will talk about - is mean. Mean (average) is probably one of the most simple and usable statistics in real life.

For example, for our audi_cars table, we can calculate the average mileage for cars manufactured in 2020. To calculate the average use AVG function followed by column name.


              123
            
SELECT AVG(mileage)
FROM audi_cars
WHERE year = 2020

Task

Using table audi_cars calculate the average price of the A4 model manufactured in 2018.

Task

Using table audi_cars calculate the average price of the A4 model manufactured in 2018.

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

Everything was clear?

The next function we will talk about - is mean. Mean (average) is probably one of the most simple and usable statistics in real life.

For example, for our audi_cars table, we can calculate the average mileage for cars manufactured in 2020. To calculate the average use AVG function followed by column name.


              123
            
SELECT AVG(mileage)
FROM audi_cars
WHERE year = 2020

Task

Using table audi_cars calculate the average price of the A4 model manufactured in 2018.

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

Section 3. Chapter 3

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