Skip to main content

join

The join command combines data from two files based on a common column.

Syntax​

qsv join <common_column> <file1> <common_column> <file2> [<options>]

Description​

The join command allows you to merge data from two files based on a common column. This is particularly useful when you need to combine information from different sources.

Options​

  • -L, --left: Perform a left join
  • -R, --right: Perform a right join
  • -I, --inner: Perform an inner join
  • -F, --full: Perform a full outer join

Interactive Example​

Join command
qsv join -R CountryCode olympics2024.csv CountryCode countries.csv \
| qsv select Rank,Country,Gold,Continent \
| qsv table

Basic Join​

Join two CSV files based on the CountryCode column:

qsv join CountryCode olympics2024.csv CountryCode countries.csv | qsv select Rank,Country,Gold,Continent | qsv table

Output:

Rank  Country        Gold  Continent
1     United States  39    North America
2     China          38    Asia
3     Japan          27    Asia
4     Great Britain  22    Europe
5     ROC            20    Europe

Left Join​

Perform a left join:

qsv join -L CountryCode olympics2024.csv CountryCode countries.csv | qsv select Rank,Country,Gold,Continent | qsv table

This will include all rows from the first file (olympics2024.csv) and only the matching rows from the second file (countries.csv).

Right Join​

Perform a right join:

qsv join -R CountryCode olympics2024.csv CountryCode countries.csv | qsv select Rank,Country,Gold,Continent | qsv table

This will include all rows from the second file (countries.csv) and only the matching rows from the first file (olympics2024.csv).

Inner Join​

Perform an inner join:

qsv join -I CountryCode olympics2024.csv CountryCode countries.csv | qsv select Rank,Country,Gold,Continent | qsv table

This will include only the rows where there is a match in both files.

Full Outer Join​

Perform a full outer join:

qsv join -F CountryCode olympics2024.csv CountryCode countries.csv | qsv select Rank,Country,Gold,Continent | qsv table

This will include all rows from both files, with null values where there is no match.

Common Use Cases​

  • Combining data from different sources
  • Merging datasets based on a common identifier
  • Enriching data with additional information

Tips​

  • Verify your joins by inspecting the output
  • Use the appropriate join type based on your data and requirements

See Also​

  • select - for selecting specific columns
  • sort - for sorting data before joining