combining similar shape files

[MikeHenson]

I have a surveyor working on a survey.  Every evening, we convert his survey file to a shape file.  Next day, he goes out and works on the same survey, he comes in and I convert it to a shape file.  Is there a way to combine these multiple files into one shape file, but not have any duplicate data?  If he surveys points 1 thru 50 on the first day, I make a shape file.  Next day, the file still has points 1 thru 50, but adds 51 thru 100. They way I have been doing it, is to just keep replaceing the file with the newest file, but I am to the point where I need to be adding data to the shape files, and if I edit the shape files in arcmap, I can't replace it with what the surveyors do.

As I re-read this, it seems like rambling!  Bottom line is I need to join shape files with no duplicate data.

Thanks for reading.

MKH

[TimWitt]

Mike,

is there a way in your survey equipment to add a timestamp? After you grab the data you use the timestamp to identify older data that you already have. You could do the same if the equipment adds a unique number to each feature.

Hope this helps!

[MikeHenson]

yes it does timestamp the data.  Being a newbie at arcmap (I a cad guy!) how would I use the time stamp to combine these files?

[TimWitt]

Once you brought the new data into your map:
1) Open the attribute table
2) right click your time stamp field and click "Sort Ascending"
3) Now select all your old data and delete it
4) Now you can merge your new data with your old data

[TimWitt]

If you don't reshape or move your old data you can also do the following:

1) Have your new and old data in your MXD.
2) Open your Arc Toolbox Analysis Tools -> Overlay -> Erase
3) As Input feature choose your NEW DATA and as Erase data choose your OLD DATA
4) You will use the output data to merge with your Old data

Again you can only use this if you don't reshape or move your data in your OLD DATA layer.

[MikeHenson]

great options guys, but heres the rub:
in the old data, I need to start adding new fields, so I can't erase the old data.  I need someway to import, but if a line already exists, I need to keep it.
Heres my drill:
we are surveying manholes and they have an old mh number.  The city i am working for, is creating new manhole numbers for them.  I assign the new mh number in the office in arcmap, so as you can see, if I import, I need to save the data that is already in the map. If I overwrite, or delete the old timestamped data, my new edits are gone.

[TimWitt]

Mike,

the erase option is still viable, since it will only remove your old data in the file you just downloaded from the surveying equipment. The data you continuously edit will stay untouched. The tool uses the data you are editing as a cutting tool, to cut it away from your just downloaded data. Once it is cut away you will only merge the newest manhole points.

Hope this clarifies it!

[MikeHenson]

ok, i think I get it.
I have 2 files. My "main" map file, and my "new" surveyed file.
I open my new file that was just surveyed, delete those points based on my time stamp
save that file and merge it with my main map file.

Am I thinking correctly?

[TimWitt]

Correct. Let me know how it goes and don't forget to mark it as answer if it works!

[MikeHenson]

just another quick question about the "merging" part.  I am still learing the difference between merge and append. Would you recommend merge?