SQL Quest

Lessons, hints, explained solutions, the in-browser PostgreSQL editor and practice answer checks in your browser are available. Graded assessments, recorded progress from answer checks and new certificates aren't available yet.

SQL Quest final assessment

The capstone exam: sixteen questions in 90 minutes, one for each core skill of the course, from reading a schema through joins, subqueries, window functions and data cleaning to schema changes, indexes, the general ledger, BI KPIs and debugging a colleague's query. Questions use eight different business databases, start gently and get harder. Every answer is graded on the public data and on a hidden copy with different rows, and data-changing questions are graded by the final state of the database. The pass mark is 75%.

Questions
16 drawn from 32
Time
90 minutes
Pass mark
75%
Retake
after 24 hours

How it works

  • Questions are drawn at random across the skills below, easiest first. A retake avoids the questions of your previous attempt wherever the question bank has others for that skill.
  • You can run queries on the real dataset as often as you like. Answers save as you type; nothing is graded until you submit.
  • The timer is kept on the server and covers writing your answers. When time runs out, your saved answers are graded as they are.
  • A query that errors or runs longer than the grader's time limit counts as not correct. A problem on our side (for example the grader being busy) never does: the attempt stays open with your answers saved, and you can submit again.
  • Each answer is graded by results on the dataset and on a hidden copy with different rows. Afterwards you see which answers passed, with the model solution and an explanation.
  • It's open-book and not proctored.

Skills covered

  • Reading a schema and its relationships
  • AND, OR, NOT and precedence
  • HAVING
  • LEFT JOIN and missing matches
  • Cardinality and row multiplication
  • EXISTS and NOT EXISTS
  • UNION, INTERSECT, EXCEPT
  • ROW_NUMBER, RANK, DENSE_RANK
  • Period-over-period comparison
  • Detecting and removing duplicates
  • Keys and constraints
  • DELETE
  • B-tree indexes
  • General ledger and trial balance
  • KPI definitions
  • Debugging queries
Not available yet. Graded assessments aren't available yet: they need SQL Quest's server-side grader, which is switched off until its security review is complete. You can still practise every lesson and check practice answers in your browser.