How to merge two CSV or Excel files

Merging means one of two things. Either the files have the same columns and you want one long table, or they share a key and you want columns from one added to the other. Both take a minute, without formulas.

Stack files with the same columns

Open NoEgress and drop all the files at once, for example twelve monthly exports. On the Start page, click Combine files and choose Append rows.

Columns are matched by name, not position, so a file with its columns in a different order still lines up. A column missing from one file is left blank for its rows.

Look up columns from another file

This is the VLOOKUP case: orders in one file, customer details in another. Click Combine files, choose Join on key, and pick the column both files share, such as customer_id.

Choose Left to keep every row of the first file, with blanks where there is no match, which is what VLOOKUP does. Choose Inner to keep only rows found in both.

Find the rows that did not match

After a lookup, check what failed to match before you trust the result. A missing customer, or an ID with a stray space, silently leaves blanks.

SELECT o.*
FROM orders o
LEFT JOIN customers c
  ON o.customer_id = c.customer_id
WHERE c.customer_id IS NULL;

Watch for repeated keys

If the lookup file has the same key twice, every matching row is duplicated in the result. VLOOKUP quietly takes the first match; a join returns both. Remove duplicates on the key in the lookup file first.