There are two ways to perform field calculations in ArcMap: through the attribute table or by using the Calculate Field geoprocessing tool. Both options use the same functionality.
To calculate date values to a field in the attribute table, follow the steps below:
- Click the Editor menu on the Editor toolbar and click Start Editing.
You can make calculations without being in an editing session; however, in that case, there is no way to undo the results.
- Click the List by Source button on the table of contents.
- Right-click the table or layer in the table of contents and choose Open Attribute Table.
- Right-click the heading for the date field and click Field Calculator.
If there is no field for date values, add a new date field by clicking the Options button and clicking the Add Field option. To add a new field, you need to exit the editing session.
- Use the Fields and Functions lists to build a date field calculation expression. You can also edit the expression in the text area below or type your own valid expression.
- Click OK.