how to select value in array with index in postgresql?

Question

id	list
1	{759-10,1147-7,931-10}
2	{719-10,117-2}

expected

id	list1	list2
1	759-10	931-10
2	719-10	117-2

Answer 1

If you just want the first and last elements, use array operations:

select id, list[1], list[cardinality(list)]
from t;

Here is a db<>fiddle.