In SQL, how can I multiple a number by an array

Question

Basically, I have an array that I need to multiply a number by each element, for example:

x float[1,2,3,4,5];
x := x * 10; --of course I get the error here

so the output would be: {10,20,30,40,50}

Answer 1

You could use unnest -> do calculation -> array_agg:

SELECT array_agg(unnest * 10)  FROM UNNEST('{1,2,3,4,5}' :: int[])

DBFiddle Demo

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To be sure about order of elements you could add WITH ORDINALITY:

SELECT array_agg(unnest * 10 ORDER BY ordinality) 
FROM UNNEST('{1,2,3,4,5}' :: int[] )WITH ORDINALITY