I am a bit new at sql server and am trying to resolve a coding issue that I have come across.

I hope there is someone out there that might be able to assist me.

I am working with zip code +4 data and am trying to range the data to reduce the size of the database from the current ~65 million lines of data.  The trick is that I need to range the data so that a single range created will include the same county and city.  The problem as illustrated below is that the data jumps back and forth with city names and therefore a simple min/max script does not work.

I believe that a looped stored procedure script needs to be used to identify each instance of a city below so that for example 90001 0001-0004 would be identified as 1, 0005-0008 would be indentified as 2, 0009-0012 would be 3, and 0013-0015 would be 4 - then a min max script would be able to capture this.  Any assistance would be terrific!

The data is currently arranged as such (example):

ZIP_CODE  PLUS_FOUR   COUNTY_NAME   CITY_NAME