nonun=# select
nonun-#  locate,
nonun-#  case when a_flag=1 then true else false end as a_flag,
nonun-#  case when b_flag=1 then true else false end as b_flag,
nonun-#  case when c_flag=1 then true else false end as c_flag
nonun-# from
nonun-#  (select
nonun(#   locate,
nonun(#   max(a_flag) as a_flag,
nonun(#   max(b_flag) as b_flag,
nonun(#   max(c_flag) as c_flag
nonun(#  from
nonun(#   (SELECT
nonun(#    locate,
nonun(#    case when a_flag is true then 1 else 0 end as a_flag,
nonun(#    case when b_flag is true then 1 else 0 end as b_flag,
nonun(#    case when c_flag is true then 1 else 0 end as c_flag
nonun(#   from test1)
nonun(#  as foo group by 1)
nonun-# as foo
nonun-# ;
 locate | a_flag | b_flag | c_flag
--------+--------+--------+--------
 001    | t      | t      | f
(1 row)

한줄로는
select locate, case when a_flag=1 then true else false end as a_flag, case when b_flag=1 then true else false end as b_flag, case when c_flag=1 then true else false end as c_flag from (select locate, max(a_flag) as a_flag, max(b_flag) as b_flag, max(c_flag) as c_flag from (SELECT locate, case when a_flag is true then 1 else 0 end as a_flag, case when b_flag is true then 1 else 0 end as b_flag, case when c_flag is true then 1 else 0 end as c_flag from test1) as foo group by 1) as foo

이고요
true 일 때는 1, false일 때는 0 으로 해서 max() 를 하면 true가 있을땐 항상 1이 나옵니다. 그럼 그걸 group by 해서 다시 case 로 true, false 로 바꿔주는 방식입니다~ 더 좋은 방법이 있을지도......