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sql

SQL

36 lessons: SELECT, JOINs, schema, analytics—practice in SQLite or DB Fiddle.

Mode
sql_sandbox
Practice
SQL sandbox
Lessons
36 units

Before you start

Structured Query Language for defining schemas, querying, joining, and aggregating relational data.

Relational databases underpin most products—SQL is the lingua franca of persisted business data.

Postgres, MySQL, SQLite, warehouses, and ORMs that still expose SQL.

Isolated SQL sandbox lessons with safe, repeatable datasets and MCQs per concept.

After programming basics—before backend frameworks that assume you can read and write queries.

Lesson order

Sequential — follow top to bottom

36 lessons are live in this track. Start from step 01 for the smoothest path.

  1. 01 intro Introduction to SQL

    beginner

    Open →
  2. 02 what-is-sql What is SQL?

    beginner

    Open →
  3. 03 relational-model-preview Relational model preview

    beginner

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  4. 04 sql-vs-nosql-preview SQL vs NoSQL preview

    beginner

    Open →
  5. 05 sql-workflow SQL workflow

    beginner

    Open →
  6. 06 select-intro SELECT fundamentals

    beginner

    Open →
  7. 07 where-filtering WHERE filtering

    beginner

    Open →
  8. 08 order-by-limit ORDER BY and LIMIT

    beginner

    Open →
  9. 09 insert-update-delete INSERT, UPDATE, DELETE

    beginner

    Open →
  10. 10 null-handling NULL handling

    beginner

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  11. 11 data-types-sql SQL data types

    beginner

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  12. 12 create-table CREATE TABLE

    beginner

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  13. 13 primary-keys Primary keys

    beginner

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  14. 14 foreign-keys Foreign keys

    intermediate

    Open →
  15. 15 constraints-sql Constraints

    intermediate

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  16. 16 indexes-intro Indexes introduction

    intermediate

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  17. 17 normalization-intro Normalization introduction

    intermediate

    Open →
  18. 18 joins-inner INNER JOIN

    intermediate

    Open →
  19. 19 joins-outer OUTER JOINs

    intermediate

    Open →
  20. 20 aggregates-group-by Aggregates and GROUP BY

    intermediate

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  21. 21 having-clause HAVING clause

    intermediate

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  22. 22 subqueries Subqueries

    intermediate

    Open →
  23. 23 union-intersect UNION and set operations

    intermediate

    Open →
  24. 24 window-functions-intro Window functions

    advanced

    Open →
  25. 25 ctes Common Table Expressions (CTEs)

    advanced

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  26. 26 case-expressions CASE expressions

    intermediate

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  27. 27 views Views

    intermediate

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  28. 28 transactions-intro Transactions introduction

    advanced

    Open →
  29. 29 explain-plans-intro EXPLAIN plans introduction

    advanced

    Open →
  30. 30 er-modeling-basics ER modeling basics

    intermediate

    Open →
  31. 31 migrations-basics Migrations basics

    intermediate

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  32. 32 sql-in-applications SQL in applications

    intermediate

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  33. 33 orm-vs-raw-sql ORM vs raw SQL

    intermediate

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  34. 34 dialects-teaser SQL dialects teaser

    intermediate

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  35. 35 interview-essentials-sql SQL interview essentials

    intermediate

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  36. 36 production-checklist-sql SQL production checklist

    advanced

    Open →