prql-exec

prql-exec is an experimental shell script to make system tools that accept SQL input easily accessible as PRQL libraries.

Getting started

Install prql-exec

git clone https://github.com/snth/prql-exec.git
cd prql-exec
ln -sf "$(pwd)/prql-exec" ~/.local/bin/prql-exec
export PRQL_LIB_PATH=".:$(pwd)"

Since without an import statement, prql-exec will just output the SQL produced, I usually just alias it to prql with:

alias prql=prql-exec

Example usage

The libraries included by default are:

Adding libraries

Libraries can be added by creating a / directory with a <Library.prql> file in it. This can then be used in PRQL queries with the import <library> statement.

Moreover, if there is a .env file in the / directory, it will be "sourced" and if there is a PRQL_EXEC_COMMAND environment variable defined in that file, then that command will be executed via eval. The generated SQL will be passed to it via a "$sql" argument. Options that can be overridden by the user at runtime should be defined in PRQL_EXEC_OPTIONS. Options that should never be overriden can simple be included in the COMMAND.

The general form of the command definition should be something like:

Please note that the quotes around $sql and the lack of quotes around $PRQL_EXEC_OPTIONS are important!

For executables that expect to receive SQL via STDIN, this can usually easily be achieved by using a command definition as follows:

PRQL_EXEC_COMMAND='echo "$sql" | <COMMAND> $PRQL_EXEC_OPTIONS'

Adding private libraries

This can be used to set up convenient aliases to internal databases. For example by creating a file _prod/.env

# _prod/.env
PGHOST=postgres
PGPORT=5432
PGDATABASE=postgres
PGUSER=postgres
PGPASSWORD=postgres
PRQL_COMPILE_OPTIONS="--target=sql.postgres --hide-signature-comment"
PRQL_EXEC_COMMAND=psql

you can easily connect to a Postres database with a command like:

prql-exec "import _prod\nfrom information_schema.sql_features"

In order to prevent you from accidentally commiting any access credentials stored in such a file to git, all libraries beginning with a leading _ are ignored in the .gitignore.

snth / prql-exec