Multi-table Joins and Comparisons
Full instructions and common questions
Multi-table Joins and Comparisons
Compare added, missing and changed fields across two original tables, or connect them with left, inner, right or full joins. Expand one-to-many matches, review the differences and export CSV, Excel or JSON.
How to use
- Import at least two CSV, TSV, JSON or XLSX tables, or load the comparison sample. Select two different original tables as left and right.
- Choose a shared key. Difference comparison requires unique, nonblank keys on both sides. Review duplicates before cleaning, exporting and reimporting.
- Compare differences or choose a left, inner, right or full join. Joins expand duplicate-key matches; blank keys never match each other.
- Check source tables, changed fields and row counts, then download CSV, Excel or JSON. Adopting a difference list makes that list the next working input.
Try an example
The comparison sample has three original A rows and four B rows. Compare by ID to find two items: DEMO-002 changes from 200 to 250, and DEMO-004 appears only on the right.
Limits and privacy
Imports allow up to 50 files, 50 MB, 100,000 rows, 300 fields and 2 million cells; result limits also apply. One-to-many joins can expand results considerably. Comparisons and joins always use the selected original tables, not automatically adopted working data. Field comparisons do not infer semantic equivalence.
Common questions
Does comparison automatically use my cleaned result?
No. It uses retained original tables. Download cleaned output and reimport it when comparing cleaned versions.
Why are duplicate keys rejected in difference comparison?
They create multiple possible counterparts for a record. Review the business rule or use one-to-many joining to inspect relationships.