Run a query in psql and output the result as CSV.
psql2csv is available on Homebrew.
$ brew install psql2csv
Grab the file psql2csv, put in somewhere in your $PATH, and make it
executable:
$ curl https://raw.githubusercontent.com/fphilipe/psql2csv/master/psql2csv > /usr/local/bin/psql2csv && chmod +x /usr/local/bin/psql2csv
psql2csv [OPTIONS] < QUERY
psql2csv [OPTIONS] QUERY
The query is assumed to be the contents of STDIN, if present, or the last argument. All other arguments are forwarded to psql except for these:
-?, --help show this help, then exit
--delimiter=DELIMITER set the field delimiter (default: ,)
--quote=QUOTE set the quote delimiter (default: ")
--escape=ESCAPE set the escape character (default: QUOTE)
--null=NULL set the string representing NULL; printed without quotes (default: empty string)
--force-quote=FORCE_QUOTE set the columns to be force quoted; comma separated list of columns or * for all (default: none)
--encoding=ENCODING set the output encoding; Excel likes latin1 (default: UTF8)
--no-header do not output a header
--timezone=TIMEZONE set the timezone config before running the query
--search-path=SEARCH_PATH set the search_path config before running the query
--dry-run print the COPY statement that would be run without actually running it
$ psql2csv dbname "select * from table" > data.csv
$ psql2csv dbname < query.sql > data.csv
$ psql2csv --no-header --delimiter=$'\t' --encoding=latin1 dbname <<sql
> SELECT *
> FROM some_table
> WHERE some_condition
> LIMIT 10
> sql
Let's assume you have a script monthly_report.sql that you run every month.
This script has a WHERE that limits the report to a certain month:
WHERE date_trunc('month', created_at) = '2019-01-01'
Every time you run it you have to edit the script to change the month you want to run it for. Wouldn't it be nice to be able to specify a variable instead?
Turns out psql does have support for variables which you can pass to psql (and
thus to psql2csv) via -v, --variable, or --set. To interpolate the
variable into the query you can use :VAR for the literal value, :'VAR' for
the value as a string, or :"VAR" for the value as an identifier.
Let's change the WHERE clause in monthly_report.sql file to use a variable
instead:
WHERE date_trunc('month', created_at) = (:'MONTH' || '-01')::timestamptz
With this change we can now run the query for any desired month as follows:
$ psql2csv -v MONTH=2019-02 < monthly_report.sql > data.csv
Philipe Fatio (@fphilipe)