SQL Constraints

Table of contents

1. 1. Primary keys and foreign keys

   0/19

   What are database constraints? A short recap of primary keys and foreign keys.

   List of exercises Start now
   1. Introduction
      1. Welcome
   2. Primary keys
      1. Creating tables with single-column primary keys
      2. Creating tables with multi-column primary keys
      3. Adding primary keys to existing tables
      4. Adding primary keys with custom names to existing tables
      5. Deleting primary keys
   3. Foreign keys
      1. Creating tables with foreign keys
      2. Adding foreign keys to existing tables
      3. Deleting foreign keys
   4. Updating and deleting with foreign keys
      1. Inserting rows with foreign key constraints
      2. Updating rows with foreign keys
      3. REFERENCES explained
      4. Database behavior with CASCADE – Updating rows
      5. Database behavior with CASCADE – Deleting rows
      6. Database behavior with various kinds of foreign keys
   5. Summary
      1. Summary
      2. Question 1
      3. Question 2
      4. Congratulations

2. 2. UNIQUE constraint

   0/15

   Learn how you can make sure that all values in a column are different.

   List of exercises Buy course
   1. Introduction
      1. Welcome
   2. Defining columns with UNIQUE
      1. UNIQUE – Introduction
      2. UNIQUE – Adding new rows
      3. UNIQUE – Adding rows with the same value
      4. UNIQUE vs. PRIMARY KEY
      5. UNIQUE – Playing around
      6. UNIQUE on multiple columns
      7. UNIQUE on multiple columns – Playing around
      8. Multiple UNIQUE constraints
   3. Adding and removing UNIQUE constraints
      1. Adding a UNIQUE constraint
      2. Adding a UNIQUE constraint with a custom name
      3. Removing a UNIQUE constraint
   4. Summary
      1. Summary
      2. Quiz
      3. Congratulations

3. 3. NOT NULL constraint

   0/9

   Learn how to make sure that a column in a database has a value.

   List of exercises Buy course
   1. Introduction
      1. Welcome
   2. NOT NULL constraint
      1. NOT NULL recap – defining a column as NOT NULL
      2. NOT NULL recap – trying to add a NULL value
      3. Adding NOT NULL to existing tables
      4. Removing NOT NULL from existing tables
      5. Adding and removing NOT NULL – exercise
   3. Summary
      1. Summary
      2. Question
      3. Congratulations

4. 4. CHECK constraint

   0/14

   Price below zero? Customer over 200 years old? Learn how CHECK constraints can ensure that information in a database is correct.

   List of exercises Buy course
   1. Introduction
      1. Welcome
   2. CHECK constraints with a simple condition
      1. Introduction
      2. CHECK – adding new values
      3. CHECK – updating rows
      4. CHECK – practice
   3. CHECK constraints with complex conditions
      1. CHECK – complex conditions
      2. Complex conditions with multiple columns
      3. Updating rows with complex constraints
      4. CHECK – practice
   4. Adding CHECK constraints to existing tables
      1. Adding CHECK constraints to existing tables
      2. Removing CHECK constraints from existing tables
   5. Summary
      1. Summary
      2. Question
      3. Congratulations

5. 5. DEFAULT constraint

   0/13

   How to provide a default value for a column.

   List of exercises Buy course
   1. Introduction
      1. Welcome
   2. Defining columns with DEFAULT
      1. DEFAULT – Introduction
      2. DEFAULT – Inserting data
      3. DEFAULT – NULL values
      4. DEFAULT – Creating tables
      5. DEFAULT and sequences – 1
      6. DEFAULT and sequences – 2
      7. DEFAULT and sequences – 3
   3. Adding DEFAULT to existing tables
      1. Adding a default value for an existing column
      2. Removing a default value from an existing column
   4. Summary
      1. Summary
      2. Review
      3. Congratulations

6. 6. Final Quiz

   0/6

   Time to test your knowledge!

   List of exercises Buy course
   1. Introduction
      1. Welcome
   2. Final Quiz
      1. Question 1
      2. Question 2
      3. Question 3
      4. Question 4
   3. Summary
      1. Congratulations

Get the Certificate of Competency in SQL

This certificate will confirm your practical SQL problem-solving skills

Obtain the Certificate Learn more