let's say we need to design a database,
first, we draw ER relationship between dept and emp.
then it will generate sql script which is used to generate
after that, if we need add one more table named "manager"
what i did is just go to sqlplus and "create table manager..."
and then add foreignkey etc.
as time goes by, i created a lot of table which is not in ER
one day, my manager ask me to give him a picture
how each table is related, i have no idea how to do that.