Can ArcMap use Excel equations in the attribute tables?

Question

I am very new to ArcMap and am learning as I go. I am trying to have one Column be the current date. In Excel I used "=Today()" and that clearly works fine but it does not seem to be updating inside of the attribute table anymore. I started this on 5/26 and the next day it seemed that they refreshed to 5/27 and I thought I had it figured out. Unfortunately, this morning I have come back and they will not update to 5/31.

• Spencer: Yes they are shapefiles! What else could I do to calculate current date within ArcMap?

Answer 1

In ArcMap you could use the field calculator to set values in the attribute table:

• Right click the layer in the table of contents, and select Open Attribute Table
• In the table, select the records you want to update (if you have no selection, all records will be updated). You can select records one by one manually, or use the menu Selection > Select By Attributes or Select By Location
• Right click on the table header of the field you want to update and select Field Calculator. Dismiss the warning about calculating outside an edit session
• Set the expression to Now() or, if you prefer Python syntax, set Parser to Python and the expression to datetime.datetime.now( )
• Click OK

Field Calculator

• Spencer: Thank you! I think I have started to piece it together. I am having to use AGE = DateDiff("d",Date,Now())/365 to get this layers age in years. I tried using "y" to get it in years but it still spit out days for me. I just want to make sure that when I open the file tomorrow, will the Now() = 6/1 or 5/31?
• Berend: Formulas are not stored in the shapefile, so tomorrow the value will still be 5/31.