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

Sorting in DESCending order

But what if we want to get the highest observation? As you remember, sorting in SQL is realized in ascending order, so the biggest values are on the bottom.

In SQL you can easily sort in reverse (descending) order. To do it use DESC keyword followed or preceded by column name. You can also put column names within the parenthesis of DESC keyword. So, there are two variants of using DESC:

DESC(col_name);
col_name DESC;

For example, we can order cars by mileage, but this time in descending order.


              123
            
SELECT *
FROM audi_cars
ORDER BY mileage DESC

Please note, that there is also ASC keyword in SQL used for ascending sorting. Since default sorting in SQL is in ascending order, this keyword is rarely used.

Task

From the audi_cars table extract all the cars sorted by column tax in descending order.

Task

From the audi_cars table extract all the cars sorted by column tax in descending order.

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

Everything was clear?

Section 4. Chapter 2

Sorting in DESCending order

But what if we want to get the highest observation? As you remember, sorting in SQL is realized in ascending order, so the biggest values are on the bottom.

DESC(col_name);
col_name DESC;

For example, we can order cars by mileage, but this time in descending order.


              123
            
SELECT *
FROM audi_cars
ORDER BY mileage DESC

Please note, that there is also ASC keyword in SQL used for ascending sorting. Since default sorting in SQL is in ascending order, this keyword is rarely used.

Task

From the audi_cars table extract all the cars sorted by column tax in descending order.

Task

From the audi_cars table extract all the cars sorted by column tax in descending order.

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

Everything was clear?

Section 4. Chapter 2

Sorting in DESCending order

But what if we want to get the highest observation? As you remember, sorting in SQL is realized in ascending order, so the biggest values are on the bottom.

DESC(col_name);
col_name DESC;

For example, we can order cars by mileage, but this time in descending order.


              123
            
SELECT *
FROM audi_cars
ORDER BY mileage DESC

Please note, that there is also ASC keyword in SQL used for ascending sorting. Since default sorting in SQL is in ascending order, this keyword is rarely used.

Task

From the audi_cars table extract all the cars sorted by column tax in descending order.

Task

From the audi_cars table extract all the cars sorted by column tax in descending order.

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

Everything was clear?

But what if we want to get the highest observation? As you remember, sorting in SQL is realized in ascending order, so the biggest values are on the bottom.

DESC(col_name);
col_name DESC;

For example, we can order cars by mileage, but this time in descending order.


              123
            
SELECT *
FROM audi_cars
ORDER BY mileage DESC

Please note, that there is also ASC keyword in SQL used for ascending sorting. Since default sorting in SQL is in ascending order, this keyword is rarely used.

Task

From the audi_cars table extract all the cars sorted by column tax in descending order.

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

Section 4. Chapter 2

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