In real life, you may work with big tables containing thousands of rows and lots of columns. For example, you may have a database with all the users who have visited your site, and you want to know all the countries that attended your site.

In SQL, to extract unique values from the column use the `DISTINCT` statement. For example, to extract unique countries from the table `visitors` use:

SQL is a domain-specific programming language widely used by data scientists, analysts, etc for manipulating and extracting necessary data. Nowadays, SQL is a must-have point in the CV for every potential analyst, data scientist. In this course, you will be introduced to the very basics of SQL.

In this section, you will be introduced to the very basics of SQL: extracting one or multiple columns from a database.

In this section, you will learn how to filter observations so only necessary rows will be extracted.

In this section, you will learn about the usage of different aggregating functions for your table, such as minimum, maximum, average... 

In this section, you will learn how to sort your table, even having filters and aggregate functions applied to a table.

In this section, you will learn about grouping observations and usage of this principle.

This chapter is designed for users who have completed the previous sections and want to consolidate knowledge.

Unique values from column

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