A few are listed in the Functions list of the field calculator once you click the Date option to the left of the list. Any Visual Basic datetime function can be used to calculate a date.You can also edit the expression in the text area below or type your own valid expression. Use the Fields list and Functions list to build a date field calculation expression.To add a new field, you need to exit the editing session. If there is no field for date values, add a new date field by clicking the Options button and then clicking the Add Field option. Right-click the heading for the date field and click Calculate Values.Right-click the layer or table you want to edit and click Open Attribute Table.Click the Source tab on the table of contents.You can make calculations without being in an editing session however, in that case, there is no way to undo the results. Click Editor on the Editor toolbar and click Start Editing.Making simple date field calculations using the field calculator Point to Settings and click Control Panel.Click the Start button on the Windows taskbar.Use the following expression in the field calculator:Ĭharacter_Field = format(, "dddd, MMMM dd, yyyy") Using this expression, the date 8/20/02 is placed in the character field as Tuesday, August 20, 2002.Ĭhanging the way ArcMap displays short format dates on Windows 2000 If you want to display the long date format (characters), you must calculate a character field equal to the long date and use it in place of the date field.Click OK on the Regional Options dialog box.Click the Short date format drop-down arrow and click the desired date format.This setting can be adjusted through Regional Options on Windows systems (see "Using two digits for the year value when calculating dates").Ĭhanging the way ArcMap displays short format dates on Windows XP When you calculate a date such as date_field = dateserial(02,8,20) and specify two digits for the year (02 in this case), your system's settings control which century is used. You can also use two digits for the year value when calculating dates. Learn more about making field calculations. To determine the amount of time that has transpired between that date and the current date, you can use the DateDiff() function (see "Calculating an attribute to the number of days between two dates" below). For example, suppose you are looking at your dataset and have dates for each record that represent the last time a reading was taken or a bill was collected. If you want to calculate an attribute equal to the number of days between two given dates, you can use the DateDiff() function in the ArcMap field calculator. The field calculator provides some of these, including Now(), which calculates the current date and time, and Date(), which calculates the current date. Any Visual Basic datetime function can be used to calculate a date. For example, the datetime 12:00:00 PM is stored in a coverage or shapefile as. However, for coverages and shapefiles, the time portion is truncated from the datetime value. Some of the functions support datetime yyyy-mm-dd hh:mm:ss AM or PM. When calculating date fields, the field calculator in ArcMap uses Visual Basic functions. ArcMap uses the system short date format (numerical) for displaying dates. Settings on your Windows system determine how the dates are displayed in ArcMap-for example, M/d/yy, MM/dd/yy, yy/MM/dd, and so on. A geodatabase formats date as datetime yyyy-mm-dd hh:mm:ss AM or PM. This topic only describes working with date fields in the attributes table and field calculator.Ī coverage or shapefile stores dates in a date field with this format: yyyy-mm-dd. This is because the field calculator in ArcMap uses Visual Basic functions and the display format depends on the system not the database. Calculating and displaying date fields in the attribute table are done in a different format and syntax. This is described in detail in the SQL Reference topic. Selecting and displaying date fields values in the Select by Attributes and similar query building dialogs are done using a SQL syntax, which will vary depending on the underlying database or data format. Whether you're displaying, calculating, or selecting date attributes, you must determine the appropriate way to work with date fields in your database. Date fields vary between data types and their display depends on your system locales.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |