Oracle SQL query to check off and compare of previous record

Is it possible to do an SQL looking at InvNumber and comparing the previous record to see if that previous record has the same invoice number and return the result 1 in the current line. For example:

Invoice table
Name InvNo
----- -----

john     1
bob      2
jane     2
ralph    3
ken      4
tom      4

The result of the SQL would be
Name InvNo Prevtrue
----- ----- --------

john     1        0
bob      2        0 
jane     2        1
ralph    3        0
ken      4        0
tom      4        1

Any posts or comments that can help in this matter would be appreciated.

Thanks,
Dave Received on Wed Aug 06 2003 - 09:07:32 CDT