select cast((Abs(Checksum(NewId()))%10) as varchar(1)) + char(ascii('a')+(Abs(Checksum(NewId()))%25)) +char(ascii('A')+(Abs(Checksum(NewId()))%25)) +left(newid(),5) from yourTable
select cast((Abs(Checksum(NewId()))%10) as varchar(1)) + char(ascii('a')+(Abs(Checksum(NewId()))%25)) +char(ascii('A')+(Abs(Checksum(NewId()))%25)) +left(newid(),5) from yourTable