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Joining Data in SQL

4.4+
214 reviews
Beginner

Level up your SQL knowledge and learn to join tables together, apply relational set theory, and work with subqueries.

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4 Hours14 Videos47 Exercises
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Course Description

Joining data is an essential skill in data analysis, enabling you to draw information from separate tables together into a single, meaningful set of results. In this comprehensive course on joining data, you'll delve into the intricacies of table joins and relational set theory, learning how to optimize your queries for efficient data retrieval.

Understand Data Joining Fundamentals

You will learn how to work with multiple tables in SQL by navigating and extracting data from various tables within a SQL database using various join types, including inner joins, outer joins, and cross joins. With practice, you'll gain the knowledge of how to select the appropriate join method.

Explore Advanced Data Manipulation Techniques

Next up, you'll explore set theory principles such as unions, intersects, and except clauses, as well as discover the power of nested queries in SQL. Every step is accompanied by exercises and opportunities to apply the theory and grow your confidence in SQL.
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  1. 1

    Introducing Inner Joins

    Free

    In this chapter, you’ll be introduced to the concept of joining tables and will explore all the ways you can enrich your queries using joins—beginning with inner joins.

    Play Chapter Now
    The ins and outs of INNER JOIN
    50 xp
    Your first join
    100 xp
    Joining with aliased tables
    100 xp
    USING in action
    100 xp
    Defining relationships
    50 xp
    Relationships in our database
    100 xp
    Inspecting a relationship
    100 xp
    Multiple joins
    50 xp
    Joining multiple tables
    100 xp
    Checking multi-table joins
    100 xp
  2. 2

    Outer Joins, Cross Joins and Self Joins

    After familiarizing yourself with inner joins, you will come to grips with different kinds of outer joins. Next, you will learn about cross joins. Finally, you will learn about situations in which you might join a table with itself.

    Play Chapter Now
    LEFT and RIGHT JOINs
    50 xp
    Remembering what is LEFT
    100 xp
    This is a LEFT JOIN, right?
    100 xp
    Building on your LEFT JOIN
    100 xp
    Is this RIGHT?
    100 xp
    FULL JOINs
    50 xp
    Comparing joins
    100 xp
    Chaining FULL JOINs
    100 xp
    Crossing into CROSS JOIN
    50 xp
    Histories and languages
    100 xp
    Choosing your join
    100 xp
    Self joins
    50 xp
    Comparing a country to itself
    100 xp
    All joins on deck
    100 xp
  3. 3

    Set Theory for SQL Joins

    In this chapter, you will learn about using set theory operations in SQL, with an introduction to UNION, UNION ALL, INTERSECT, and EXCEPT clauses. You’ll explore the predominant ways in which set theory operations differ from join operations.

    Play Chapter Now
    Set theory for SQL Joins
    50 xp
    UNION vs. UNION ALL
    100 xp
    Comparing global economies
    100 xp
    Comparing two set operations
    100 xp
    At the INTERSECT
    50 xp
    INTERSECT
    100 xp
    Review UNION and INTERSECT
    50 xp
    EXCEPT
    50 xp
    You've got it, EXCEPT...
    100 xp
    Calling all set operators
    100 xp
  4. 4

    Subqueries

    In this closing chapter, you’ll begin by investigating semi-joins and anti-joins. Next, you'll learn how to use nested queries. Last but not least, you’ll wrap up the course with some challenges!

    Play Chapter Now
    Subquerying with semi joins and anti joins
    50 xp
    Multiple WHERE clauses
    100 xp
    Semi join
    100 xp
    Diagnosing problems using anti join
    100 xp
    Subqueries inside WHERE and SELECT
    50 xp
    Subquery inside WHERE
    100 xp
    WHERE do people live?
    100 xp
    Subquery inside SELECT
    100 xp
    Subqueries inside FROM
    50 xp
    Subquery inside FROM
    100 xp
    Subquery challenge
    100 xp
    Final challenge
    100 xp
    The finish line
    50 xp

In the following tracks

Associate Data Analyst in SQLAssociate Data Engineer in SQLData Scientist in PythonData Scientist in RSQL FundamentalsSQL Server Fundamentals

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Collaborators

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Amy Peterson
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James Chapman
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Izzy Weber

Prerequisites

Intermediate SQL
Maham Khan HeadshotMaham Khan

Senior Data Scientist, YouView TV

Maham is a Data Scientist on a mission to make data skills accessible for everyone. She's worked on creating toolkits and exploring experimental applications of data science for urban analytics, disaster risk management, and climate change mitigation at the World Bank. She has a background in Experimental Psychology and Philosophy from the University of Oxford and Urban Data Science from NYU.
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*4.4
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  • Agustín A.
    3 months

    Excellent flowing of the course through nice theory modules and great practices !

  • Alexandr I.
    5 months

    I significantly improved my skills in SQL with this course. Thank you!

  • Paola O.
    5 months

    This is an excellent resource that can be used to refresh or expand your knowledge of SQL. The exercises provided can be challenging, but are complex enough to allow you to practice while contemplating real-world scenarios. The AI technology utilized to explain why certain code may be incorrect is incredibly helpful.

  • Kevin B.
    5 months

    SQL joins is an essential competency that enables efficient data extraction, transformation and analysis from relational databases. I really enjoyed the course.

  • Stanimir D.
    7 months

    Maybe more daily practice challenges - otherwise nothing to complain about.

"Excellent flowing of the course through nice theory modules and great practices !"

Agustín A.

"I significantly improved my skills in SQL with this course. Thank you!"

Alexandr I.

"This is an excellent resource that can be used to refresh or expand your knowledge of SQL. The exercises provided can be challenging, but are complex enough to allow you to practice while contemplating real-world scenarios. The AI technology utilized to explain why certain code may be incorrect is incredibly helpful."

Paola O.

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