drop table if exists _tmp_enum8
;;
create table _tmp_enum8 (
    `е` Nullable(Enum8('A' = 1, 'B' = 2))
) Engine = Log
;;
insert into _tmp_enum8 (е)
select е from (
    select 'A' as e
    union ALL
    select 'B'
    union all
    select NULL
)


SQL Error [62]: ClickHouse exception, code: 62, host: 127.0.0.1, port: 14407; Code: 62, e.displayText() = DB::Exception: Syntax error: failed at position 25 (line 1, col 25): е)
select e from (
    select 'A' as e
    union ALL
    select 'B'
    union all
    select NULL
). Unrecognized token (version 19.16.2.2 (official build))