codequest.
No account needed
Color theme

YOUR SQL LEARNING PATH

A little more SQL.
A little more confidence.

One idea at a time, with examples you can follow and checkpoints to see what’s clicking. New here? Begin with chapter one. Know a little already? Jump right in.

Before you start

No SQL experience needed. Begin by reading a table and selecting columns. Later chapters introduce joins, grouping, windows, and recursive queries using SQLite.

Review a foundation whenever you need it: Rows, columns, and SELECT

Start chapter one Ready for the final?
14 open chapters. Your progress is saved as you go.

Your chapters

Choose any starting point
  1. 01

    Read a table and choose columns

    Beginner

    Understand rows and columns before filtering, joining, or grouping them.

    Start here, or skip ahead
    Open chapter: Read a table and choose columns
  2. 02

    Select rows with a clear order

    Beginner

    Express a question as projection, filtering, and ordering in SQLite.

    Open whenever you’re ready
    Open chapter: Select rows with a clear order
  3. 03

    Missing values and three-valued logic

    Beginner

    Handle NULL without confusing it with zero or empty text.

    Open whenever you’re ready
    Open chapter: Missing values and three-valued logic
  4. 04

    Keys, constraints, and valid rows

    Intermediate

    Encode data rules that every writer must respect.

    Open whenever you’re ready
    Open chapter: Keys, constraints, and valid rows
  5. 05

    Join tables without losing the question

    Intermediate

    Predict row multiplication and preserve unmatched records.

    Open whenever you’re ready
    Open chapter: Join tables without losing the question
  6. 06

    Existence tests and correlated questions

    Intermediate

    Express whether related rows exist without multiplying the outer result.

    Open whenever you’re ready
    Open chapter: Existence tests and correlated questions
  7. 07

    Aggregate at the right grain

    Intermediate

    Summarize groups without double-counting or mixing row levels.

    Open whenever you’re ready
    Open chapter: Aggregate at the right grain
  8. 08

    Set operations and duplicate meaning

    Intermediate

    Choose whether repeated rows remain observations or collapse into membership.

    Open whenever you’re ready
    Open chapter: Set operations and duplicate meaning
  9. 09

    CTEs and windowed analysis

    Advanced

    Separate query stages while retaining individual rows.

    Open whenever you’re ready
    Open chapter: CTEs and windowed analysis
  10. 10

    Dates, ranges, and deterministic periods

    Intermediate

    Define time windows without losing boundary events.

    Open whenever you’re ready
    Open chapter: Dates, ranges, and deterministic periods
  11. 11

    Recursive CTEs and termination

    Advanced

    Build iterative query results with an explicit stopping rule.

    Open whenever you’re ready
    Open chapter: Recursive CTEs and termination
  12. 12

    Updates, upserts, and affected rows

    Advanced

    Apply changes to the intended records while preserving key meaning.

    Open whenever you’re ready
    Open chapter: Updates, upserts, and affected rows
  13. 13

    Transactions, constraints, and query plans

    Advanced

    Protect data invariants and investigate performance with evidence.

    Open whenever you’re ready
    Open chapter: Transactions, constraints, and query plans
  14. 14

    Indexes and evidence-based query tuning

    Advanced

    Connect an index to a query’s actual filtering and ordering needs.

    Open whenever you’re ready
    Open chapter: Indexes and evidence-based query tuning

PUT IT TOGETHER

Final assessment & certificate

32 multiple-choice questions and 2 written coding problems. Pass the knowledge section at 80% overall and at least 50% in every chapter area, complete and review the written practice, and meet the attempt-integrity checks to unlock your certificate.

The certificate records a CodeQuest foundations assessment. Written work is self-reviewed; identity and independent proficiency are not verified.

Open final assessment

Take an issuer-recorded assessment with a verifiable certificate

Continue the original guided missions