Variable in dateadd function snowflake - sql

Question

I have a query like this:
With cte as(
Select min(date1) as min_date,
max(date1) as max_date,
id,
city,
time_id
From some_table
Group by id, city, time_id
),
range as
(select dateadd('month', row_number()over(order by null), (select min_date from cte)) as date_expand
From table(generator (row_count => 12*36))))
Select * from range;
It gives this error:
Single row subquery returns more than one row.
Is there a way to pass a variable in the 3rd argument of dateadd function? Because my cte will return many min_date based on the group by clause. TIA

Answer 1

Yes, sub-select in SELECT need to only return one row, you have many rows in your CTE.
You query makes more sense to me if you did something like this:
With some_table as (
SELECT * FROM VALUES
(1, 'new york', 10, '2020-01-01'::date),
(1, 'new york', 10, '2020-02-01'::date),
(2, 'christchurch', 20, '2021-01-01'::date)
v(id, city, time_id, date1)
), cte as (
Select
min(date1) as min_date,
max(date1) as max_date,
id,
city,
time_id
FROM some_table
GROUP BY 3,4,5
), range as (
SELECT
id, city, time_id,
dateadd('month', row_number()over(partition by id, city, time_id ORDER BY null), min_date) as date_expand
FROM table(generator(rowcount =>12*36))
CROSS JOIN cte
)
Select * from range;
but if your CTE was changing to be like this:
With cte as (
Select
min(date1) as min_date,
max(date1) as max_date
FROM some_table
), range as (
SELECT
dateadd('month', row_number()over(ORDER BY null), (select min_date from cte)) as date_expand
FROM table(generator(rowcount =>2*4))
)
Select * from range;
this would work, as there is only one min_date value returned.
OR you could find the smallest of the min_dates like:
WITH cte as (
Select
min(date1) as min_date,
max(date1) as max_date,
id,
city,
time_id
FROM some_table
GROUP BY 3,4,5
), range as (
SELECT
dateadd('month', row_number()over(ORDER BY null), (select min(min_date) from cte)) as date_expand
FROM table(generator(rowcount =>2*3))
)
Select * from range;