SQL Queries and Data Management: Free Course

About this course

Build practical SQL reasoning in this free database course from Khan Academy. All fifteen source recordings remain available, covering table creation, inserting data, querying, filtering, aggregation, conditional results, joins and data changes. The examples make it possible to follow a query from the question it answers to the rows it returns. A small database is enough to practice the main techniques and learn why two similar-looking queries can produce different results.

Course at a glance

What you’ll learn

• Create a table, insert records and retrieve selected data.
• Filter and combine conditions with the demonstrated query methods.
• Use aggregation, grouping and HAVING to answer a defined question.
• Explore CASE, subqueries, inner joins, left joins and self-joins.
• Change records and table structure using the operations taught in the course.

Skills you’ll gain

• SQL
• Data queries
• Aggregation
• Relational joins
• Query logic
• Data management

Course Overview

The complete recorded SQL edition covers foundations and progressively richer query behavior. A learner can study how tables represent records, then connect filtering and aggregation with a practical information request. The relation-focused recordings explain different ways of joining tables, including multiple joins, left outer joins and self-joins. Other videos cover conditional results, subqueries and changing stored data or a table definition. All source entries, including the introductory pronunciation recording, are preserved. The searchable classroom list provides a way to revisit the relevant operation while working on an independent database exercise.

How to study the course

• Videos 1–3: this part of the source list includes “More complex queries with AND/OR” through “Welcome to SQL”. State the intended input, operation and result. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.
• Videos 4–7: this part of the source list includes “Changing rows with UPDATE and DELETE” through “Querying the table”. Reproduce a demonstration before modifying it. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.
• Videos 8–11: this part of the source list includes “Altering tables after creation” through “Querying IN subqueries”. Trace behavior and investigate unexpected output. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.
• Videos 12–15: this part of the source list includes “Restricting grouped results with HAVING” through “Joining related tables with left outer joins”. Check the example with a changed condition. Keep a brief working note, revisit an unclear explanation and test one example before moving to another part of the material.

Who is this for?

This course suits learners studying the specific programming or computing topic. It also provides a recorded reference for revisiting a topic after an earlier lesson or study attempt. Choose examples appropriate to your background and allow time to work through the method instead of judging understanding only by how familiar the terminology sounds.

Before you start

Use a suitable practice environment for the language or tool shown in the recordings. Earlier programming knowledge is useful for topic courses that build on variables, functions or data structures.

Put the lessons into practice

Create a small fictional database with two related tables, such as products and stock records. Insert enough rows to produce different query results. Write a query for a simple selection, another for a grouped summary and one that combines related records. Include a case where a matching related row is absent and explain the result of the join you choose. Test a change to a record in your practice database and confirm its effect with a query. Keep the question, SQL and expected result together so that you can investigate an unexpected answer systematically.

This optional study activity is provided by WikiFree for independent practice. Keep your working notes and use the relevant classroom recording to check a step, definition or interpretation. It is not an instructor-marked assignment.

Certificate / Assessment

Watching the public videos and using WikiFree completion tracking does not award a certificate, academic credit, an examination voucher or instructor assessment. Use your practice output to review what you can explain and repeat independently. The recorded lessons provide study material; completion tracking records your progress through that material.

Frequently asked questions

Provider: Khan Academy. Videos play from the Khan Academy channel on YouTube.