Displaying updated data from Excel
Is there a way to automatically display updated values without going into Layer properties and refreshing manually? I have excel sheet that I use to color in certain states (catagories, uniqe values) when I go into the data and remove a state it automatically takes it out but when I add data with a different value I have to manually go into properties and refresh the data to get it to add the new state. I actually tried to change and sort by "value" but if the new state has a different value I run into the same problem. Any ideas? I have over 200 of these maps and it would be so much easier to have them refresh on opening rather than having to refresh them manually. Thanks!
Mapping Center Answer:
There's no "out of the box" functionality to do what you're asking. All of the symbology methods depend on reading the data once to set up the legend and again each time draw the features.
If you know ahead of time the full set of unique values that you are ever going to use, you can create a legend that will always work, and the features will always draw. The idea is to create a layer file with this complete definition of the unique values and symbols and load that layer each time, and then set data source to your latest data.
The drawback to that is your legend will show every symbol, even if it doesn't appear on the map (see the legend limiter arcscripts sample which will address that problem).
Longer term it would make sense to write a script or create a model that converts your data from Excel into a geodatabase, where you can define a custom domain for your unique values field (customized from a list of the possible values--or the values you find each day in your data) and that will give you a standard dataset for your MXD to refer to. The MXD would need some custom ArcObjects code that gets run once each time the document loads--and that would rebuild the layer, optimizing it against your latest data. I mention it because if you've got that many maps to make the effort will be worth it.
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