sql server 2008 - Import unique combination of rows -

i working huge database updated every day new entries. in order find duplicates use either checksum using hashbytes function , custom remove duplicates function, or import unique entries using merge function. encounter difficulties when set of entries considered unique business information.

e.g.:

date           name      adress 2013-07-01     peter     ad1 2013-07-01     peter     ad2 2013-07-01     peter     ad3 2013-07-02     peter     ad1 2013-07-02     peter     ad2 2013-07-02     peter     ad3 2013-07-04     peter     ad1 2013-07-04     peter     ad3 2013-07-05     peter     ad1 2013-07-05     peter     ad2 2013-07-05     peter     ad3 

the desired result be

date           name      adress 2013-07-01     peter     ad1 2013-07-01     peter     ad2 2013-07-01     peter     ad3 2013-07-04     peter     ad1 2013-07-04     peter     ad3 2013-07-05     peter     ad1 2013-07-05     peter     ad2 2013-07-05     peter     ad3  

it simplified case, in general import function should able consider combination of several attributes recognising unique set of rows.