Python Implementation of Pipelined Relational Query Language (PRQL)
Project description
PyPrql
Python implementation of PRQL.
Documentation of PRQL is at https://github.com/max-sixty/prql
Installation
pip install pyprql
CLI
Usage:
prql 'connection_string'
prql 'postgresql://user:password@localhost:5432/database'
Examples:
prql 'sqlite:///chinook.db'
Try it out:
curl https://github.com/qorrect/PyPrql/blob/main/resources/chinook.db?raw=true -o chinook.db
prql "sqlite:///chinook.db"
PRQL> show tables
pyprql.to_sql
query='''
from employees
filter country = "USA"
derive [
gross_salary: salary + payroll_tax,
gross_cost: gross_salary + benefits_cost
]
filter gross_cost > 0
aggregate by:[title, country] [
average salary,
sum salary,
average gross_salary,
sum gross_salary,
average gross_cost,
sum_gross_cost: sum gross_cost,
row_count: count salary
]
sort sum_gross_cost
filter row_count > 200
take 20
'''
from pyprql import to_sql
sql = to_sql(query)
print(sql)
SELECT AVG(salary),
SUM(salary),
AVG(salary + payroll_tax),
SUM(salary + payroll_tax),
AVG(salary + payroll_tax + benefits_cost),
SUM(salary + payroll_tax + benefits_cost) as sum_gross_cost,
COUNT(salary) as row_count,
salary + payroll_tax as gross_salary,
(salary + payroll_tax) + benefits_cost as gross_cost
FROM `employees` employees_e
WHERE country="USA" AND (gross_salary+benefits_cost)>0
GROUP BY title, country
HAVING row_count >200
ORDER BY sum_gross_cost
LIMIT 20
Differences from the spec
The parser is only able to parse casts in select statements insde of [ ], so
select foo | as float
will fail, it must be wrapped in brackets as a single item list.
select [ foo | as float ]
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