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FROM FILE TO VERIFIED RESULT

Combine two CSV tables using a shared identifier

Match two CSV tables with a left, inner or full join. Review unmatched keys, duplicate expansion and column names before exporting.

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or drop files · 10 MB per file

Import settings apply only to files opened next; existing datasets stay unchanged. No-header files receive column_1, column_2, and so on while keeping the first record. Exports include those column names.

Join

Join two tables by a key and review matching and output size.

Interactive example · fictional data

Bring related fields into one table

Example input · products.csv
skuname
00123Blue·mug
00456Red·cap
Example input · inventory.csv
skustock
004568
0012320

Dots show spaces; ∅ means empty. Swipe tables to see all columns.

Ready to play

This small example does not change your open files.

Or open your own files. Data is processed in this browser.

See the result, then try it

Join

Interactive example · fictional data

Bring related fields into one table

Example input · products.csv
skuname
00123Blue·mug
00456Red·cap
Example input · inventory.csv
skustock
004568
0012320

Dots show spaces; ∅ means empty. Swipe tables to see all columns.

Ready to play

This small example does not change your open files.

Rules, limits and questions

Use a join to bring related fields together, such as a product list and a supplier update. Choose what should happen to unmatched records and inspect duplicate-key expansion before creating a combined table.

Your result: A joined dataset with a reviewed schema and explicit matching behavior.

Steps

  1. Open both supplier examples and select the left and right tables. Choose the matching key in each input.
  2. Choose Left to retain left-side records, Inner for matched records only, or Full to include both unmatched sides. Review normalization and duplicate-key warnings.
  3. Check the projected output and renamed overlapping fields. Confirm any intentional duplicate expansion, retain the result, and continue with a filter or export.

Download example CSVs

These files contain fictional data. You can also close help and choose “Try sample files” in the toolbar.

Expected example result

  • Exact matching on sku produces 2 matched keys: 00123 and 00789.
  • Left join keeps 3 left-side records; Inner returns 2 records; Full includes 4 keys.
  • 00456 has no right-side match, while 00900 is included only by the Full join.

Scope and limits

  • A join adds fields; it does not choose the correct price or automatically update a store.
  • Blank keys do not establish a match. Duplicate keys can multiply output rows and require an explicit decision.
  • The workspace checks projected size before constructing a large result.

Questions

Why can a join produce more rows than either input?

When the same key appears multiple times in both tables, each left match can pair with multiple right records. For one key with 2 left records and 3 right records, there are 6 matched combinations. They are created only after you explicitly acknowledge duplicate expansion and the projected result passes size limits. Review whether those combinations represent a valid task before confirming them.

Can I clean or filter the joined result?

Yes. The retained result is a dataset in the same workspace. Select it and continue without downloading and reopening the file.

Related tool instructions

Close help and use the workspace tools to continue with your current files. The links below open in a new tab.

Full cell value

Review input record

No files open. Refreshing clears the session.

Session limits: 8 source files, 30 MB combined input and 16 retained datasets. Output is limited to 250,000 rows and 2,000,000 cells.

Data stays in this page's memory. Original files are never overwritten. A download action starts the browser download; confirm the saved file yourself.