SQL

The 50-year-old skill every data job still screens for.

SQL in depth: querying and filtering, joins, aggregation, subqueries and CTEs, window functions, schema design, indexes and data modification - with practice resources on every topic.

Your progress0/20 topics · 0%

Saved on this device — no account needed.

6 stages20 topics₹0 to follow
  1. 1

    Query Foundations

    Read any table with precision.

    1–2 weeks0/4
  2. 2

    Joins

    Combine tables and predict the row count.

    1–2 weeks0/4
  3. 3

    Aggregation

    Turn transactions into metrics.

    1–2 weeks0/3
  4. 4

    Subqueries, CTEs & Windows

    The SQL that marks you as experienced.

    2 weeks0/4
  5. 5

    Schema & Performance

    Understand any database you're dropped into.

    1–2 weeks0/4

    Build: Ten questions, one dataset

    Load a public dataset into Postgres/SQLite and answer ten business questions; publish the queries with comments.

  6. 6

    Prove It

    Verified SQL on the resume.

    1 week0/1

  7. Final stop: prove it.

    Knowledge without proof is just a claim. Take the free SQL certification — a timed, scored assessment with a public verification link recruiters can check in one click.