SQL is the most important language for data scientists.

I’ve summarized in this document the top 5 SQL skills to master for manipulating data.

Top 5 SQL skills to master for manipulating data

1- Subqueries:

Subquery is a query nested within another query to provide intermediate results that the outer query can use. They can be used in various parts of a SQL statement, such as the SELECT, FROM, WHERE, and HAVING clauses.

2- Case statements

CASE statements are used to handle conditional logic directly in the SQL queries. They allow to perform different actions based on different conditions, making the queries more dynamic and flexible.

3- JOINs

JOINs help combine multiple tables based on matching keys. There are different types of JOINs, each serving a specific purpose:

INNER JOIN: Matches only rows with a common value in both tables.

LEFT JOIN: Includes all rows from the left table and matching rows from the right tab.

RIGHT JOIN: Includes all rows from the right table and matching rows from the left tab.

FULL JOIN: Includes all rows from both tables, regardless of match.

4- Common Table Expressions (CTEs)

CTEs (Common Table Expressions): powerful feature in SQL that allow to create temporary result sets within a query using the WITH clause. This can make complex queries easier to read and maintain.

5- Window Functions

Window Functions perform calculations across a set of table rows related to the current row, without collapsing rows like GROUP BY does. They allow  to perform complex calculations such as running totals, moving averages, and rankings within a specified window of rows.