Clean data without hiding your decisions
Clean data with a record of what you changed and why.
Reviewed: 2026-10-03
Source-based teaching example · Fictional data
Narration: Microsoft Mark · locally synthesized

00:00:00.000 — What you will learn

Clean data with a record of what you changed and why.

Visual description:
Clean data with a record of what you changed and why.

00:00:05.875 — The idea

Use the supplied key and duplicate rule. Preserve unresolved records. Report how much of the data the result actually covers.

Visual description:
Use the supplied key and duplicate rule. Preserve unresolved records. Report how much of the data the result actually covers.

00:00:17.458 — One useful term

Cleaning log. A record of accepted, changed, excluded and unresolved rows with reasons.

Visual description:
A record of accepted, changed, excluded and unresolved rows with reasons.

00:00:27.292 — A worked example · 1

R1 with amount ten appears twice. R2 has fifteen; R3 is missing its amount. The declared rule treats the identical repeated R1 ID as a duplicate.

Visual description:
R1 with amount ten appears twice. R2 has fifteen; R3 is missing its amount. The declared rule treats the identical repeated R1 ID as a duplicate.

00:00:41.417 — A worked example · 2

The known accepted total is twenty-five.

Visual description:
The known accepted total is twenty-five.

00:00:47.083 — Your turn to think

Does that known total establish the full total including R3? Pause and decide before continuing.

Visual description:
Does that known total establish the full total including R3?
Pause the video if you need more time.

00:01:04.458 — Why this answer works

No. R3 remains unresolved. Do not treat a repeated item description as a duplicate ID without a rule.

Visual description:
No. R3 remains unresolved. Do not treat a repeated item description as a duplicate ID without a rule.

00:01:15.167 — Check 1

Use the declared key.

Visual description:
Use the declared key.

00:01:19.542 — Check 2

Keep missing and disputed rows.

Visual description:
Keep missing and disputed rows.

00:01:24.542 — Check 3

State incomplete coverage.

Visual description:
State incomplete coverage.

00:01:29.333 — Now try a different case

Open the lesson and try its different practice case. Use every check in the full task. Watching alone does not mark the lesson complete.

Visual description:
Open the lesson
Try the new case
Check and revise
The full task and its requirements are in the linked lesson.