Notice: This page requires JavaScript to function properly.
Please enable JavaScript in your browser settings or update your browser.Aliases | Selecting
SQL Basics
course content

Course Content

SQL Basics

SQL Basics

1. Selecting
The very first meet with the databaseSELECTing certain columnsLIMITing resultsUnique values from columnUnique values from multiple columnsHow many?How many unique?AliasesTables aliases
2. Filtering
Word filteringNumber filteringCombining conditionsFiltering by numeric intervalMultiple filtering on one columnLIKE filteringNOT like this!
3. Aggregating
MINimal and MAXimal valuesSUMming valuesMean valuesROUNDing
4. Sorting
Sorting by one columnSorting in DESCending orderThe cheapest carSorting by multiple columns
5. Grouping
What is grouping?More aggregate statistics!Grouping by multiple columnsThe cheapest combinationHAVING some conditionsLeast consuming carsFiltering group size
6. Practicing
Challenge: Unique combinationsChallenge: Average Q-series cars priceChallenge: The cheapest new A-series carsChallenge: Relation between engine size and fuel consumptionChallenge: Mileage and manufacture year - is there relation?Challenge: Average price for each model and yearChallenge: The most expensive transmission + engine size combinations

bookAliases

The outputs of the last two tasks were single columns with single values. If you noticed, this column had a name count, which is not, to be honest representative. Seems like it's only a matter of taste. But in the future, when you will work with multiple tables, will join one table to another, the same names will be a huge problem. Even from the point of interpreting the data.

In SQL you can easily declare a new name to a column by using AS statement. For example,


              
12

            
SELECT COUNT(DISTINCT(country)) AS "number of countries"
FROM visitors
copy

This query will return a single value in the single column named number of countries, which is much readable than count.

Please note, that the aliases you use must be placed within double-quotes. Using single quotes will result in SQL error!

Task

Extract unique types of fuel consumed by cars (column fueltype) and name this column as "Fuel type".

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 1. Chapter 8
toggle bottom row

bookAliases

The outputs of the last two tasks were single columns with single values. If you noticed, this column had a name count, which is not, to be honest representative. Seems like it's only a matter of taste. But in the future, when you will work with multiple tables, will join one table to another, the same names will be a huge problem. Even from the point of interpreting the data.

In SQL you can easily declare a new name to a column by using AS statement. For example,


              
12

            
SELECT COUNT(DISTINCT(country)) AS "number of countries"
FROM visitors
copy

This query will return a single value in the single column named number of countries, which is much readable than count.

Please note, that the aliases you use must be placed within double-quotes. Using single quotes will result in SQL error!

Task

Extract unique types of fuel consumed by cars (column fueltype) and name this column as "Fuel type".

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 1. Chapter 8
toggle bottom row

bookAliases

The outputs of the last two tasks were single columns with single values. If you noticed, this column had a name count, which is not, to be honest representative. Seems like it's only a matter of taste. But in the future, when you will work with multiple tables, will join one table to another, the same names will be a huge problem. Even from the point of interpreting the data.

In SQL you can easily declare a new name to a column by using AS statement. For example,


              
12

            
SELECT COUNT(DISTINCT(country)) AS "number of countries"
FROM visitors
copy

This query will return a single value in the single column named number of countries, which is much readable than count.

Please note, that the aliases you use must be placed within double-quotes. Using single quotes will result in SQL error!

Task

Extract unique types of fuel consumed by cars (column fueltype) and name this column as "Fuel type".

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

The outputs of the last two tasks were single columns with single values. If you noticed, this column had a name count, which is not, to be honest representative. Seems like it's only a matter of taste. But in the future, when you will work with multiple tables, will join one table to another, the same names will be a huge problem. Even from the point of interpreting the data.

In SQL you can easily declare a new name to a column by using AS statement. For example,


              
12

            
SELECT COUNT(DISTINCT(country)) AS "number of countries"
FROM visitors
copy

This query will return a single value in the single column named number of countries, which is much readable than count.

Please note, that the aliases you use must be placed within double-quotes. Using single quotes will result in SQL error!

Task

Extract unique types of fuel consumed by cars (column fueltype) and name this column as "Fuel type".

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 1. Chapter 8
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
some-alt