HELP .. DISTINCT and a join - usually indicates loose programming. Replace by EXISTS

Can someone give me an example where you
would use an exists rather then a distinct in a sql stmt?

DISTINCT and a join - usually indicates loose programming. Replace by EXISTS


ex: select distinct (conv_acct_id) from lookup_exception

what would the exists stmnt look like?

select distinct(conv_acct_id) from lookup_exception where exists(select something from somewhere where condition=true);