Timestamp-format in SQL

Hi,

Is it possible to change the format in which you update/insert a timestamp
value.
for example :

current format (YYYY-MM-DD) :

insert into TEST
 (Birthday,Comment)
 values ('1974-05-26','doei..')

I want this format (YYYYMMDD) :

insert into TEST
 (Birthday,Comment)
 values ('19740526','doei..')

Thanks

Arno.