Grouping - is arranging observations into sub-groups based on unique values in some column. For example, we can group our `audi_cars` table by `transmission` column (contains 3 unique values). There will be observations within each subgroup. So, what's the point of grouping?

In SQL grouping is often used in pair with some aggregate function within `SELECT`. For example, we can calculate the average `price` for each `transmission` type.

SELECT AVG(price), transmission
FROM audi_cars
GROUP BY transmission

This will return all the transmissions types with average prices within each group.

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.

What is grouping?

Solution

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What is grouping?

Solution