Single item is coerced into a list

PRQL

from employees
select salary

SQL

SELECT
  salary
FROM
  employees

Same as above but with salary in a list:

PRQL

from employees
select [salary]

SQL

SELECT
  salary
FROM
  employees

Multiple items

PRQL

from employees
derive [
  gross_salary = salary + payroll_tax,
  gross_cost = gross_salary + benefits_cost
]

SQL

SELECT
  *,
  salary + payroll_tax AS gross_salary,
  salary + payroll_tax + benefits_cost AS gross_cost
FROM
  employees

Same as above but split into two lines:

PRQL

from employees
derive gross_salary = salary + payroll_tax
derive gross_cost = gross_salary + benefits_cost

SQL

SELECT
  *,
  salary + payroll_tax AS gross_salary,
  salary + payroll_tax + benefits_cost AS gross_cost
FROM
  employees