ydb/yql/essentials/tests/sql/suites/case/case_opt_cond.sql

select case when cast('true' as Bool) then 'FOO1' else 'BAR1' end
union all
select case when cast('false' as Bool) then 'FOO2' else 'BAR2' end
union all
select case when NULL then 'FOO3' else 'BAR3' end;