This article applies only to a Microsoft Access database (.mdb).
Prior to Microsoft Access 2000, Microsoft Access used a Jet database (.mdb) file to store both database objects (tables, queries, and relationships) as well as the Microsoft Access-specific objects (forms, reports, macros, and modules). Microsoft Access stored its specific objects in Jet system tables, specifically the MSysObjects and MSysModules (or MSysModules2) tables. The DateUpdate column in the MSysObjects table is responsible for storing an object's last modification date and is the column that the DAO LastUpdated property uses to return an object's last modified date. When a user modified and saved an object in earlier versions, Microsoft Access notified the Jet database engine that the object had been modified, and Jet updated the DateUpdate column to the current date and time.
Microsoft Access 2000 introduced Access project (.adp) files, which have the capability of connecting directly to Microsoft SQL Server databases without using the Jet database engine. Because ADP files do not use the Jet database engine (or the Access Database Engine), Access could not use the same storage format previously used in Jet databases for Access-specific objects. It had to store them in a new OLE doc storage format that is accessible in both Jet databases and Access projects. When the user initially creates a new Microsoft Access specific-object, such as a form), the database engine still enters the current date and time into the DateCreate and DateUpdate columns in the MSysObjects table. However, when the user modifies and saves the object, Microsoft Access does not notify the database engine; therefore, the DateUpdate column always stays the same.
Additionally, you may have noticed that the Database window (in versions prior to Access 2007) and the Navigation Pane in Access 2007 or Access 2010 displays the correct date and time for an object's last modification. This is because Microsoft Access uses its own internal mechanism for storing the date created and date modified, independent of the database engine. Unfortunately, Microsoft Access does not expose this information in its object model; therefore, there is no programmatic way to get to this information in Microsoft Access.
Steps to Reproduce the Behavior
- Start Microsoft Access, and then create a new, blank database.
- Create a new, blank form in Design view.
- Add a text box to the form.
- Save the form as frmLastUpdated, and then close it.
- In Access 2003 and earlier versions of Access, select the View menu and click Details. In Access 2007 or Access 2010, right-click on the Category header in the Navigation Pane on the left and click View By Details. This displays the Modified and Created dates for each object.
Note that both the Modified and Created columns for the frmLastUpdated form are set to the same date and time.
- Press CTRL+G to open the Immediate window in Visual Basic Editor. (In Access 2007 or Access 2010, you must first enable the content or the database must be in a trusted location.)
- Type the following line into the Immediate window, and then press ENTER:Note that the date and time returned corresponds to the Modified and Created columns in the Database window.
- Press ALT+F11 to switch back to Microsoft Access.
- Open the frmLastUpdated form in Design view.
- Add a second text box to the form, and then save and close it.
Note that the Modified column in the Database window contains an updated date and time for the form.
- Repeat steps 7 and 8.