xsv join name data.csv name emp-ids.csv

The join command merges two CSV files on a key column, taking the column name, first file, second column name, and second file as four arguments. Here data.csv and emp-ids.csv share the name field, and matching rows combine their columns. Rows without a match in the other file are dropped by default. Add --left to keep all rows of the first file, like a SQL LEFT JOIN.