Multiply a column with each values of an array - postgresql

Question

How to multiply a column value with each element present in the array without using loop?
I have tried using the for each loop which iterates over the loop and multiplying each element with the column value.
CREATE OR REPLACE FUNCTION
public.test_p_offer_type_simulation1(offers numeric[])
RETURNS TABLE(sku character varying, cannibalisationrevenue double
precision, cannibalisationmargin double precision)
LANGUAGE plpgsql
AS $function$ declare a numeric []:= offers;
i numeric;
begin
foreach i in array a loop return QUERY
select
base.sku,
i * base.similar_sku,
.................
Suppose I have a column name 'baseline', and have an array [1,2,3], I want to multiply a baseline column value where its id =1 with each element of the array.
Example:::
id | baseline
----+----------
1 | 3
suppose I have an array with values [2,3,4]; I want to multiply baseline= 3 with (3 *2) , (3*3), (3*4). and return 3 rows after multiplication with values 6, 9, 12.
The output should be:
id | result| number
----+-------+---------
1 6 2
1 9 3
1 12 4

Answer 1

OK, according to your description, just use unnest function, the example SQL as below:
with tmp_table as (
select 1 as id, 3 as baseline, '{2,3,4}'::int[] as arr
)
select id,baseline*unnest(arr) as result,unnest(arr) as number from tmp_table;
id | result | number
----+--------+--------
1 | 6 | 2
1 | 9 | 3
1 | 12 | 4
(3 rows)
You can just replace the CTE table_tmp above to your real table name.