Course overview
A subquery is a query nested inside another query. Subqueries are useful to data practitioners for scaling and making more powerful queries. The main reason we have subqueries is the need to combine information from multiple tables. Information in a relational database isn’t stored in a single table; it’s shared between several tables.
In this course, you’ll learn various types of subqueries, how to use them, and why they are so valuable: scalar subquery, multi-rows subquery and multi-columns subquery. You’ll also learn how to write common table expressions in SQL.
Best of all, you’ll learn by doing — you’ll practice and get feedback directly in the browser.
Key skills
- Nesting a query inside another query
- Employing different types of subqueries
- Employing common table expressions
- Scaling your project with complex queries
Course outline
SQL Subqueries [6 lessons]
Scalar Subqueries in SQL 1h
Lesson Objectives- Extract a single value from a subquery
- Employ a single value subquery in your queries
- Identify why subqueries are useful
Multi-row and Multi-column Subqueries in SQL 1h
Lesson Objectives- Extract multiple rows from a subquery
- Extract multiple columns from a subquery
- Scale your project with multi-row subqueries
Nested and Correlated Subqueries in SQL 1h
Lesson Objectives- Nest a subquery inside another subquery
- Write dependent subqueries
- Write effective queries
Common Table Expression in SQL 1h
Lesson Objectives- Write Common Table Expressions (CTEs)
- Write Recursive Common Table Expression
Views in SQL 1h
Lesson Objectives- Explain the concept and application of views in SQL
- Create views
- Query views
- Create views from views
- Drop views
Guided Project: Customers and Products Analysis Using SQL 1h
Lesson Objectives- Expand your portfolio using real-world data
Projects in this course
Guided Project: Customers and Products Analysis Using SQL
Work on a real-life project using SQL
The Dataquest guarantee
Dataquest has helped thousands of people start new careers in data. If you put in the work and follow our path, you’ll master data skills and grow your career.
We believe so strongly in our paths that we offer a full satisfaction guarantee. If you complete a career path on Dataquest and aren’t satisfied with your outcome, we’ll give you a refund.
Master skills faster with Dataquest
Go from zero to job-ready
Learn exactly what you need to achieve your goal. Don’t waste time on unrelated lessons.
Build your project portfolio
Build confidence with our in-depth projects, and show off your data skills.
Challenge yourself with exercises
Work with real data from day one with interactive lessons and hands-on exercises.
Showcase your path certification
Impress employers by completing a capstone project and certifying it with an expert review.
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