Partition and order a window
See this course’s project requirements
A reproducible SQLite attendance analysis with per-session rank, running totals and prior-period changes that retains every original row.
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 grouped-versus-windowed result choice.
- An independent session sequence with deterministic ordering.
- A week rank record 3,1,1 with declared tie behavior.
- Running-total rows A 8,20,32 and B 6,15.
- A row-comparison record with honest missing-baseline handling.
- A reproducible window-analysis 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
The query partitions by session and orders running/LAG calculations by week, id. B’s running total starts with 6, not after A 32.
PARTITION BY separates independent groups; ORDER BY defines the sequence for order-sensitive calculation. A stable tie-breaker such as id makes the chronological sequence explicit.
Partition and order a window — original worked practice
PARTITION BY separates independent groups; ORDER BY defines the sequence for order-sensitive calculation. A stable tie-breaker such as id makes the chronological sequence explicit.
The query partitions by session and orders running/LAG calculations by week, id. B’s running total starts with 6, not after A 32.
1. Step 1
Find PARTITION BY session in the query.
You should see: A and B have independent window contexts.
This keeps the rule and its observable result together.
2. Step 2
Read ORDER BY week, id.
You should see: Week comes first; stable ID breaks same-week ties.
This keeps the rule and its observable result together.
3. Step 3
Trace first B row.
You should see: Its running value is 6 and previous is NULL.
This keeps the rule and its observable result together.
4. Step 4
Record the partition and order contract.
You should see: An independent session sequence with deterministic ordering.
This keeps the rule and its observable result together.
What to finish
An independent session sequence with deterministic ordering.
Watch for this
Leaving equal sort keys unordered when a running result depends on a deterministic sequence.
How can I tell I understand it?
Explain and demonstrate the required distinction: PARTITION BY separates independent groups; ORDER BY defines the sequence for order-sensitive calculation. A stable tie-breaker such as id makes the chronological sequence explicit. Show a changed input and the expected result without weakening this contract.
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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.
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