Course Library · Lesson 6 of 6

Digital · Guided lesson

Deliver a reproducible answer brief

About 37 minutes · 7 reading + 30 practice and checks

Time includes reading, practice, and questions. Extra videos or further study are optional.

See this course’s project requirements

Answer whether one assigned workshop session can accommodate six additional bookings using your accumulated query collection.

Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.

What to include

Include the complete original two-table fixture and dictionary.
Show filtering, ordering and grouped summaries with expected results.
Demonstrate both session-preserving and venue-preserving joins.
Detect an invalid test record and record missing-data limits.
Deliver the decision query with reproducible output and interpretation.

Review and revise

Use these criteria to check your work and choose what to improve.

Question fit: row and group meanings match the decision.
Query correctness: results follow from explicit SQL or accurate traces.
Quality: totals reconcile and missing matches are explained.
Reproducibility: fixture, queries and limits travel with the answer.

Open the full course project

Want more background?

Before you begin

The idea in everyday life

A brief should let another reader reproduce the answer instead of simply trusting a number. The fictional organizer wants to know whether existing sessions provide room for another group of six. Your previous queries already show availability and missing assignments. You will reuse them to answer the practical question while explaining why total capacity alone is insufficient.

The idea

A data answer is a chain from question to rows to calculation to interpretation.

Try it

One step at a time.

Use the sample or information you have permission to use. Keep your work as you go. You can pause between steps.

1
State the decision: find a single assigned-venue session with at least six open seats. Explain that six seats scattered across sessions do not necessarily fit a group that must attend together.
2
Combine the availability filter with sites.code IS NOT NULL to require a matched venue. Reuse the site-name left join for readable output. Select session ID, venue name and available seats, with explicit ordering.
3
Reuse the quality checks before reporting results. Keep the original fixture, all SQL statements and expected outputs together so a reader can rebuild the small database.
4
Write three sentences: the supported answer, its arithmetic and its limitation. Distinguish recorded bookings from verified current availability; the fictional fixture is not a live booking system.
5
Assemble your final collection from the dictionary, filters, summary, joins and quality note. Include a paper trace if no database was used, and label it accurately rather than claiming an executed query.

Example

See how it works.

Fictional final query:

sql

SELECT sessions.id, sites.name,
       sessions.seats - sessions.booked AS available
FROM sessions LEFT JOIN sites ON sessions.site = sites.code
WHERE sessions.seats - sessions.booked >= 6
  AND sites.code IS NOT NULL
ORDER BY available DESC, sessions.id;

Only session 3 at South qualifies with nine available seats. Session 4 has six open seats but no assigned venue, so it is excluded by the stated rule. The brief recommends reviewing session 3 for a six-person group, leaving three recorded seats. It does not promise a reservation or assume that the stored figures have been updated in real time.

Check your work

Did you cover these?

The question requires one assigned session.
Final output is session 3, South, 9.
Execution versus manual tracing is labeled accurately.

Your work

What to finish

A reproducible SQL answer brief with fixture, five query types, quality note and limitations.

Common mistake

Watch for this

Treating a query result as permission to book, publish or change real records.

How can I tell I understand it?

A reader can reproduce the result and explain why another row was excluded.

Finish this lesson

Pass the check. We’ll save the progress.

Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

Go to the knowledge check

Tools, templates, and lesson sources

Tools and templates

Tools open in a new tab so you can keep your place here.

SQL starter packFictional database setup, ten reference queries, expected tables, a blank answer brief, and a runner using Python’s built-in SQLite.

Your course project worksheetA downloadable text worksheet with each lesson’s working output, space for your answers, and the shared final-project checklist. Save your own copy.

Sources and further reading

Explore the references behind this lesson.

Harvard CS50 — Introduction to Databases with SQL

Source & access notes · checked 2026-09-10

Opened university OpenCourseWare overview; verified querying, relationships, design and optimization topics. Used as optional further study, with original fixtures here.

Access: Free OpenCourseWare reading and videos. External grading or progress services may require accounts; optional verified certificates have separate enrollment and may be paid. This course awards no Harvard credit or affiliation.

Reuse: Linked for reference. Examples, activities and assessments here are original; free access alone does not grant permission to reuse source text or branding.

SQLite — SELECT reference

Source & access notes · checked 2026-09-10

Opened official SELECT documentation covering WHERE, GROUP BY, joins, ORDER BY and NULL behavior. All supplied queries target SQLite syntax.

Access: Free public reading; no account or certificate is required for this Life Starter course.

Reuse: Linked for reference. Examples, activities and assessments here are original; free access alone does not grant permission to reuse source text or branding.

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