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

Tables aliases

As for columns, you can also assign some alias to the table name. It is very useful when you work with multiple tables at once, as they may have identical names.

To assign an alias to a table name use the same syntax as for columns. For example,


              12
            
SELECT column1, column2
FROM table_name AS t

With this technique, you can refer to certain columns by using alias.column. It also works for the whole table name. For example,


              12
            
SELECT t.column1, t.column2
FROM table_name AS t

and


              12
            
SELECT table_name.column1, table_name.column2
FROM table_name

queries will return the same result. It's all about usability.

Task

Extract columns model, price, fueltype, and mpg from audi_cars table. Use a alias for the table and extract columns using this alias. Print first 10 rows.

Task

Extract columns model, price, fueltype, and mpg from audi_cars table. Use a alias for the table and extract columns using this alias. Print first 10 rows.

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

Everything was clear?

Section 1. Chapter 9

Tables aliases

As for columns, you can also assign some alias to the table name. It is very useful when you work with multiple tables at once, as they may have identical names.

To assign an alias to a table name use the same syntax as for columns. For example,


              12
            
SELECT column1, column2
FROM table_name AS t

With this technique, you can refer to certain columns by using alias.column. It also works for the whole table name. For example,


              12
            
SELECT t.column1, t.column2
FROM table_name AS t

and


              12
            
SELECT table_name.column1, table_name.column2
FROM table_name

queries will return the same result. It's all about usability.

Task

Extract columns model, price, fueltype, and mpg from audi_cars table. Use a alias for the table and extract columns using this alias. Print first 10 rows.

Task

Extract columns model, price, fueltype, and mpg from audi_cars table. Use a alias for the table and extract columns using this alias. Print first 10 rows.

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

Everything was clear?

Section 1. Chapter 9

Tables aliases

As for columns, you can also assign some alias to the table name. It is very useful when you work with multiple tables at once, as they may have identical names.

To assign an alias to a table name use the same syntax as for columns. For example,


              12
            
SELECT column1, column2
FROM table_name AS t

With this technique, you can refer to certain columns by using alias.column. It also works for the whole table name. For example,


              12
            
SELECT t.column1, t.column2
FROM table_name AS t

and


              12
            
SELECT table_name.column1, table_name.column2
FROM table_name

queries will return the same result. It's all about usability.

Task

Extract columns model, price, fueltype, and mpg from audi_cars table. Use a alias for the table and extract columns using this alias. Print first 10 rows.

Task

Extract columns model, price, fueltype, and mpg from audi_cars table. Use a alias for the table and extract columns using this alias. Print first 10 rows.

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

Everything was clear?

As for columns, you can also assign some alias to the table name. It is very useful when you work with multiple tables at once, as they may have identical names.

To assign an alias to a table name use the same syntax as for columns. For example,


              12
            
SELECT column1, column2
FROM table_name AS t

With this technique, you can refer to certain columns by using alias.column. It also works for the whole table name. For example,


              12
            
SELECT t.column1, t.column2
FROM table_name AS t

and


              12
            
SELECT table_name.column1, table_name.column2
FROM table_name

queries will return the same result. It's all about usability.

Task

Extract columns model, price, fueltype, and mpg from audi_cars table. Use a alias for the table and extract columns using this alias. Print first 10 rows.

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

Section 1. Chapter 9

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