prefer_* セッション設定

SET prefer_column_name_to_alias = 1;
SELECT t1.id + 10 AS id, id AS x
FROM (SELECT 1 AS id) AS t1, (SELECT 1 AS k) AS t2, (SELECT 2 AS id) AS t3;

┌─id─┬──x─┐
│ 11 │ 11 │
└────┴────┘

SET prefer_column_name_to_alias = 0;
SELECT avg(number) AS number, max(number) FROM numbers(10);

Received exception from server (version 21.5.1):
Code: 184. DB::Exception: Received from localhost:9000. DB::Exception: Aggregate function avg(number) is found inside another aggregate function in query: While processing avg(number) AS number.

SET prefer_column_name_to_alias = 1;
SELECT avg(number) AS number, max(number) FROM numbers(10);

┌─number─┬─max(number)─┐
│    4.5 │           9 │
└────────┴─────────────┘