Use distinct with decode

Question

i use this
select count(distinct a.id_client) cant,
sum(decode(b.sex,'W',mount)) mount
from credit a,client b
where a.id_client = b.id_client
CANT MOUNT
11383 97305111.8
but if i want to use decode in the count, like this
select count(decode(b.sex,'W',distinct a.id_client)) cant,
sum(decode(b.sex,'W',mount)) mount
from credit a,client b
where a.id_client = b.id_client;
select count(decode(b.sex,'W',distinct a.id_client)) cant,
ERROR at line 1:
ORA-00936: missing expression
and if i use this query without distinct clause it work fine
select count(decode(b.sex,'W', a.id_client)) cant,
sum(decode(b.sex,'W',mount)) mount
from credit a,client b
where a.id_client = b.id_client;
CANT MOUNT
21668 97305111.8
what can i do, i want to get the quantity of clients by sex in diferents columns but i don't want to use a group by clause like this
select b.sex,count(a.id_client) cant
from credit a,client b
where a.id_client = b.id_client
group by b.sex

Answer 1

Try this.
SELECT COUNT(DISTINCT DECODE(b.sex,'W',a.id_client,null)) cant,
       SUM(DECODE(b.sex,'W',mount)) mount
FROM credit a,client b
WHERE a.id_client = b.id_client;