Actually i need to get

User’s name
Contact’s name and it’s department id and it’s Authority id and
authority name.
so i done following query.
but its so long.
I don’t know about join queries.
so pls help me how can i implemend join query instead of below query…

user = UserInfo.find_by_id(user_id)

=>Using this query I get user.first_name

contact = UserInfo.find_by_id(contact_id)

=>Using this query I get contact.first_name and contact.department_id

authority = PrivilegeInfo.find(:first, :conditions => [ "user_id =? and
department_id =? ", contact_id,contact.department_id])

=>Using this query I get authority.authority_id

authority_name = UserInfo.find_by_id(authority.authority_id)

=>Using this query I get authority_name.first_name

Thanks in advance