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Introduction to Relational Databases in SQL

Learn how to create one of the most efficient ways of storing data - relational databases!

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4 Hours13 Videos45 Exercises85,774 Learners
3600 XP

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Course Description

You’ve already used SQL to query data from databases. But did you know that there's a lot more you can do with databases? You can model different phenomena in your data, as well as the relationships between them. This gives your data structure and consistency, which results in better data quality. In this course, you'll experience this firsthand by working with a real-life dataset that was used to investigate questionable university affiliations. Column by column, table by table, you'll get to unlock and admire the full potential of databases. You'll learn how to create tables and specify their relationships, as well as how to enforce data integrity. You'll also discover other unique features of database systems, such as constraints.

  1. 1

    Your first database

    Free

    In this chapter, you'll create your very first database with a set of simple SQL commands. Next, you'll migrate data from existing flat tables into that database. You'll also learn how meta-information about a database can be queried.

    Play Chapter Now
    Introduction to relational databases
    50 xp
    Attributes of relational databases
    50 xp
    Query information_schema with SELECT
    100 xp
    Tables: At the core of every database
    50 xp
    CREATE your first few TABLEs
    100 xp
    ADD a COLUMN with ALTER TABLE
    100 xp
    Update your database as the structure changes
    50 xp
    RENAME and DROP COLUMNs in affiliations
    100 xp
    Migrate data with INSERT INTO SELECT DISTINCT
    100 xp
    Delete tables with DROP TABLE
    100 xp
  2. 2

    Enforce data consistency with attribute constraints

    After building a simple database, it's now time to make use of the features. You'll specify data types in columns, enforce column uniqueness, and disallow NULL values in this chapter.

    Play Chapter Now
    Better data quality with constraints
    50 xp
    Types of database constraints
    50 xp
    Conforming with data types
    100 xp
    Type CASTs
    100 xp
    Working with data types
    50 xp
    Change types with ALTER COLUMN
    100 xp
    Convert types USING a function
    100 xp
    The not-null and unique constraints
    50 xp
    Disallow NULL values with SET NOT NULL
    100 xp
    What happens if you try to enter NULLs?
    50 xp
    Make your columns UNIQUE with ADD CONSTRAINT
    100 xp
  3. 3

    Uniquely identify records with key constraints

    Now let’s get into the best practices of database engineering. It's time to add primary and foreign keys to the tables. These are two of the most important concepts in databases, and are the building blocks you’ll use to establish relationships between tables.

    Play Chapter Now
    Keys and superkeys
    50 xp
    Get to know SELECT COUNT DISTINCT
    100 xp
    Identify keys with SELECT COUNT DISTINCT
    100 xp
    Primary keys
    50 xp
    Identify the primary key
    50 xp
    ADD key CONSTRAINTs to the tables
    100 xp
    Surrogate keys
    50 xp
    Add a SERIAL surrogate key
    100 xp
    CONCATenate columns to a surrogate key
    100 xp
    Test your knowledge before advancing
    100 xp
  4. 4

    Glue together tables with foreign keys

    In the final chapter, you'll leverage foreign keys to connect tables and establish relationships that will greatly benefit your data quality. And you'll run ad hoc analyses on your new database.

    Play Chapter Now
    Model 1:N relationships with foreign keys
    50 xp
    REFERENCE a table with a FOREIGN KEY
    100 xp
    Explore foreign key constraints
    100 xp
    JOIN tables linked by a foreign key
    100 xp
    Model more complex relationships
    50 xp
    Add foreign keys to the "affiliations" table
    100 xp
    Populate the "professor_id" column
    100 xp
    Drop "firstname" and "lastname"
    100 xp
    Referential integrity
    50 xp
    Referential integrity violations
    50 xp
    Change the referential integrity behavior of a key
    100 xp
    Roundup
    50 xp
    Count affiliations per university
    100 xp
    Join all the tables together
    100 xp

In the following tracks

Data AnalystData Analyst Data Analyst Data EngineerSQL for Database AdministratorsSQL Server for Database Administrators

Collaborators

Sumedh PanchadharChester IsmayMona Khalil

Prerequisites

Introduction to SQL
Timo Grossenbacher Headshot

Timo Grossenbacher

Project Lead Automated Journalism at Tamedia

Timo Grossenbacher is a project lead for automated journalism at Swiss publisher Tamedia. Prior to that, he used to be a data journalist working with the Swiss Public Broadcast (SRF), where he used scripting and databases for almost every data-driven story he published. He also teaches data journalism at the University of Zurich and is the creator of rddj.info – resources for doing data journalism with R. Follow him at grssnbchr on Twitter or visit his personal website.
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