Pipes

Pipes — the connection between transforms that make up a pipeline — can be either line breaks or a pipe character (|).

In almost all situations, line-breaks pipe the result of a line’s transform into the transform on the following line. For example, the filter transform operates on the result of from employees (which is just the employees table), and the select transform operates on the result of the filter transform.

PRQL

  1. from employees
  2. filter department == "Product"
  3. select [first_name, last_name]

SQL

  1. SELECT
  2.   first_name,
  3.   last_name
  4. FROM
  5.   employees
  6. WHERE
  7.   department = 'Product'

In the place of a line-break, it’s also possible to use the | character to pipe results, such that this is equivalent:

PRQL

  1. from employees | filter department == "Product" | select [first_name, last_name]

SQL

  1. SELECT
  2.   first_name,
  3.   last_name
  4. FROM
  5.   employees
  6. WHERE
  7.   department = 'Product'

A line-break doesn’t create a pipeline in a couple of cases:

  • within a list (e.g. the derive examples below),
  • when the following line is a new statement, which starts with a keyword of func, let or from.