Write a targeted UPDATE
See this course’s project requirements
A local SQLite seat-transfer exercise with before/after totals, an all-or-nothing update, a deliberately rejected change and rollback evidence.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- A seat-transfer contract with total 10 preserved.
- Two targeted updates with a declared completion boundary.
- A committed all-or-nothing transfer record.
- A 5, B 5 and no active transaction after rejection.
- A parameterized update/lookup record with known-ID validation.
- A checked seat-transfer transaction packet.
Review and revise
Use these criteria to check your work and choose what to improve.
- The implementation or declared simulation follows the supplied contract and retains inspectable original inputs.
- Normal, boundary and rejected cases are recorded with expected versus observed results.
- The changed case has a correct explanation and does not rely on hidden state.
- The project includes source, outputs, instructions and honest tool, privacy and verification limits.
Want more background?
The idea in everyday life
For A 8, B 2, execute UPDATE seats SET quantity=quantity-3 WHERE group_id='A' inside a practice transaction; it changes A to 5 while B leaves 2 until the second update.
WHERE chooses the rows to modify. Omitting it can change every row. The provided SQL uses quantity=quantity-? with group_id=? so only the declared source is affected.
Write a targeted UPDATE — original worked practice
WHERE chooses the rows to modify. Omitting it can change every row. The provided SQL uses quantity=quantity-? with group_id=? so only the declared source is affected.
For A 8, B 2, execute UPDATE seats SET quantity=quantity-3 WHERE group_id='A' inside a practice transaction; it changes A to 5 while B leaves 2 until the second update.
1. Step 1
Locate Set versus WHERE in the supplied statement.
You should see: Set names quantity change; WHERE selects A.
This keeps the rule and its observable result together.
2. Step 2
Trace one statement’s intermediate state.
You should see: A 5, B 2, total 7 is not yet a complete transfer.
This keeps the rule and its observable result together.
3. Step 3
Trace a paired recipient update.
You should see: B becomes 5 and total returns 10.
This keeps the rule and its observable result together.
4. Step 4
Explain why the intermediate state must not be committed alone.
You should see: Two targeted updates with a declared completion boundary.
This keeps the rule and its observable result together.
What to finish
Two targeted updates with a declared completion boundary.
Watch for this
Omitting the WHERE clause and changing every seat group instead of the named group.
How can I tell I understand it?
Explain and demonstrate the required distinction: WHERE chooses the rows to modify. Omitting it can change every row. The provided SQL uses quantity=quantity-? with group_id=? so only the declared source is affected. Show a changed input and the expected result without weakening this contract.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
You’ll get an explanation for each answer. Signed in? Your results save to your account.
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 checkTools, templates, and lesson sources
Tools and templates
Tools open in a new tab so you can keep your place here.
Sources and further reading
Explore the references behind this lesson.
Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
Report a problem with this lesson
Tell us what went wrong. Please leave out personal information and private project contents.