How to display all unique data in a column + to it any random value from another column?

Question

PostgreSQL

There is a table:
id code key
1 11 111
2 11 222
3 22 333
4 22 444
5 33 555
...
i.e. the key column contains unique values, the code column repeats
You need to make a request so that the response is of the format
code key
11 222
22 333
33 555
i.e. you need to display all unique values ​​from the code column + one first found value from the key column.

Answer 1

SELECT DISTINCT ON ("code") "code", "key"
FROM table_name