Computed columns and CTEs sometimes lead to missing column #5354
Description
What happened?
When a query results in several CTEs, a computed column may be duplicated in a child CTE without its' column sources. This leads to Referenced column "..." not found as the column is not there anymore.
PRQL input
prql target:sql.postgres
from employees
derive `year` = s'EXTRACT(year from {`hire_date`})'
derive { `year_label` = f"Year {`year`}" }
derive { `city` = case [ this.`city` == "Calgary" => "A city", true => this.`city` ] }
derive { `city` = case [ this.`city` == "Edmonton" => "Another city", true => this.`city` ] }
group {`year`, `year_label`} (take 1)
select {this.`year_label`}SQL output
WITH table_0 AS (
SELECT
CONCAT(
'Year ',
EXTRACT(
year
from
hire_date
)
) AS year_label,
CASE
WHEN city = 'Calgary' THEN 'A city'
ELSE city
END AS _expr_0,
city
FROM
employees
)
SELECT
DISTINCT ON (
EXTRACT(
year
from
hire_date
),
year_label
) year_label
FROM
table_0Expected SQL output
WITH table_0 AS (
SELECT
CONCAT(
'Year ',
EXTRACT(
year
from
hire_date
)
) AS year_label,
EXTRACT(
year
from
hire_date
) as year_or_expr_1_or_something,
CASE
WHEN city = 'Calgary' THEN 'A city'
ELSE city
END AS _expr_0,
city
FROM
employees
)
SELECT
DISTINCT ON (
year_or_expr_1_or_something,
year_label
) year_label
FROM
table_0MVCE confirmation
- Minimal example
- New issue
Anything else?
Example is reproducible in the playground. Removing the last select is enough to get out of the CTE topology and therefore to not fail.