Welcome. In this course, we're going to talk about window functions in PostgreSQL. SQL window functions make building complex aggregations much simpler. They are so powerful that they serve as a dividing point in time: people talk about SQL before window functions and SQL after window functions.

After window functions and Common Table Expressions were introduced to the language, SQL has become Turing complete.

Window functions are a relatively new addition to SQL. They were originally standardized with SQL:2003. Postgres has supported window functions since PostgreSQL 8.4. It was the first major database system to do so.

This course is designed for beginning database analysts, PostgreSQL developers who want to keep their knowledge of SQL current, students taking classes in relational databases and anyone who wants to learn SQL window functions in PostgreSQL. Do keep in mind, however, that this course in not intended for complete SQL beginners. We assume you already know how to:

• query a single table.
• query multiple tables with JOIN data from multiple tables.
• sort and group rows.
• and use the HAVING statement.

If you have not written a single SQL query before, we recommend that you take our Basics of PostgreSQL course first.