Spreadsheet Comparison

Find missing rows between two CSV files

A smaller row count tells you something is different. Matching IDs tells you which records need checking.

By Spreadsheet Comparison 4 minute read

To find missing rows between two CSV files, match records using an identifier that exists in both exports, then review the records found in only one file. Comparing row numbers will give misleading results if either file has been sorted differently.

Check both directions

Suppose Monday.csv contains the synthetic IDs A101, A102 and A103. Tuesday.csv contains A103, A101 and A104. Both files have three rows, but they do not contain the same records. A102 is only in Monday.csv; A104 is only in Tuesday.csv. A row-count check alone misses both differences.

Decide which file is the baseline before describing anything as added or removed. If the files are exports from different systems rather than different dates, use their filenames in your report. “Only in CRM.csv” is more precise than calling the record deleted.

Find missing records in Spreadsheet Comparison

  1. Open both CSV files and confirm their filenames.
  2. Map the ID fields, even if one is called Customer ID and the other client_id.
  3. Select that mapping as the row key. Use several fields if a single ID repeats legitimately.
  4. Run the comparison and select the filter for records found only in the first file. Repeat for the second file.
  5. Search a known missing ID and inspect its full row before exporting the filtered report.

Why a changed record can look missing

A key must stay stable. If you use an email address as the key and it changes, the old and new rows have different identities. They can appear as one record on each side instead of one changed record. A permanent customer ID avoids that problem when both systems preserve it.

Leading zeros also matter. An exported ID of 00102 is not automatically the same identifier as 102. Inspect the source values rather than adding zeros based on guesswork. Repeated IDs need a separate check: one file may contain the same ID twice while the other contains it once.

Missing from the export is not always missing from the system

Check date ranges, active-record filters and export permissions. A record might be on another worksheet or excluded by a source filter. Record those conditions alongside your findings so somebody else can reproduce the comparison.

For repeated IDs, read how duplicate keys affect row matching. If the IDs themselves are difficult to choose, start with the key selection guide.