MeritKeep

Audit a table you have been told to trust

You have inherited a `customers` table that a downstream team relies on. Audit it and report what is wrong: duplicate identities, orphaned foreign keys, NULLs in fields the schema says are required in practice, and values outside plausible ranges. Report findings ranked by how much damage each would do downstream, with a reproducing query for each.

Part of the SQL & Data Analysis course~75 minutesEvidence: a write-upWe mark it against a checklist you can read first
01 · What counts as done

What you have to hand in

  • At least four distinct classes of problem are checked.
  • Every finding names the table, column and affected row count.
  • Every finding ships with a query the reader can run themselves.
  • Findings are ranked, and the ranking is justified.
  • Each finding is verified against the source tables, so none of them is an artefact of the audit's own joins.
02 · How it will be marked

The checklist, published before you start

We score your work against each line below, and every score has to quote the part of your work it is based on. You read all of it first, so you can argue with any score on the specifics.
  • Checks cover the real failure modes30% of the grade

    The audit looks for duplicates, orphaned references, NULLs in required fields, and out-of-range values.

    1. AbsentOnly one class of problem is checked.
    2. DevelopingTwo classes checked; obvious gaps remain.
    3. Competent— this is the pass markAll four classes checked.
    4. StrongAll four, plus at least one domain-specific check the brief did not name.
  • Findings are specific and actionable25% of the grade

    Each finding names the table, column and row count affected.

    1. AbsentFindings are vague ("some data is bad").
    2. DevelopingFindings name the table but not the scale.
    3. Competent— this is the pass markEvery finding names table, column and affected row count.
    4. StrongFindings also include a reproducing query someone else can run.
  • Findings survive scrutiny25% of the grade

    Reported problems are genuine, not artefacts of the audit query itself.

    1. AbsentSeveral findings are caused by the audit's own joins.
    2. DevelopingOne finding is a false positive.
    3. Competent— this is the pass markAll findings verified against the source tables.
    4. StrongVerified, with the verification shown.
  • Findings are ranked by impact20% of the grade

    The reader can tell which problem to fix first and why.

    1. AbsentAn unranked list.
    2. DevelopingRanked, but the ranking is not justified.
    3. Competent— this is the pass markRanked by a stated notion of impact.
    4. StrongRanked, justified, and tied to a concrete downstream consequence.
03 · What this proves

The skills a pass would prove

Pass, and these skills count as proven, with this piece of work attached as the evidence.

This brief is part of the SQL & Data Analysis course

Starting it starts the course: every skill above, in the order they depend on each other, with this brief at the end as the thing you hand in — marked against the checklist you have just read and nothing else.

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