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Joining Data in SQL

4.4+
146 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
77,056 Learners

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Course Description

Joining data is an essential skill which enables us to draw information from separate tables together into a single, meaningful set of results. Learn to supercharge your queries using table joins and relational set theory in this course on joining data.

In this course, you’ll learn how to:
✓ Work with more than one table in SQL
✓ Use inner joins, outer joins and cross joins
✓ Leverage set theory, including unions, intersect, and except clauses
✓ Create nested queries

Every step is accompanied by exercises and opportunities to apply the theory and grow your confidence in SQL.
  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

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Collaborators

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Amy Peterson
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Izzy Weber
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James Chapman

Prerequisites

Intermediate SQL
Maham Khan HeadshotMaham Khan

Senior Data Science Content Developer at DataCamp

Hi, I am a Data Scientist and Senior Content Developer at DataCamp, on a mission to make data skills accessible for everyone. Most recently, I've 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. I have a background in Experimental Psychology and Philosophy from the University of Oxford, and Urban Data Science from NYU.
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Don’t just take our word for it

*4.4
from 146 reviews
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  • Mun l.
    8 days

    This course teaches me how to write SQL in a most efficient way.

  • Trenado F.
    9 days

    Excellent Course

  • Jherson C.
    12 days

    Great course !

  • Chad N.
    12 days

    I've already recommended DataCamp to a few friends and family members.

  • Dan C.
    15 days

    I like that you have a sandbox during problems resolving

"This course teaches me how to write SQL in a most efficient way."

Mun l.

"Excellent Course"

Trenado F.

"Great course !"

Jherson C.

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