Reconcile two exports using stable keys

A row-by-row visual comparison breaks when sorting changes. Join on an explicit key and report records found on only one side.

Prepare the workbook

Keep an unchanged source copy and explain column meanings, units and date boundaries. Use a spreadsheet or data role with compatible local tools, or the prepared sandbox. Ask for a rejected-row report instead of silently deleting inconvenient records. OfficeCubs text previews do not recalculate formulas; open the final workbook in a spreadsheet application and check representative formulas and totals.

Inputs for this workflow: before.csv and after.csv with a stable record_id.

Work through the task

1. Check key uniqueness on both sides.
2. Separate added, removed and changed records.

A brief you can adapt

Create reconciliation.xlsx with Added, Removed, Changed and Invalid keys sheets. Include old and new values for each changed field. Preserve both inputs.

The filenames above are examples. Replace them with your actual inputs and destination before submitting the task.

Review the deliverable

Check a known changed record and confirm that duplicate keys are treated as exceptions rather than arbitrary matches.

Where this approach can fail

A nonunique join key can multiply rows and create false changes.

For the related desktop setup, see missing document tools.