https://stackoverflow.com/questions/14133332
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RussianAccording to MSDN, extended properties can be used for the following:
- Specifying a caption for a table, view, or column. Applications can then use the same caption in a user interface that displays information from that table, view, or column.
- Specifying an input mask for a column so that applications can validate data before running a Transact-SQL statement. For example, the required format for a postal code or telephone number column can be specified in the extended property.
- Specifying formatting rules for displaying the data in a column.
- Recording a description of specific database objects that applications can display to users. For example, the descriptions may be used in a data dictionary application or report. Specifying the size and window location at which a column should be displayed.
MS Access does not compare directly with SQL Server, because it is a rapid application database development tool that generally uses a Jet/ACE database back-end, whereas SQL Server is an RDBMS. In MS Access you have a range of tools such as forms and reports that can be used to provide most of the properties above.
For (1), you can specify a caption for a column in table design view, but you will generally find it is better to use forms for names of columns, tables and queries (views).
For (2), you can specify validation rules for each field (column) in table design view and also in any form you create.
For (3), you can specify format in table design view and in forms.
For (4), you can add description to objects that can be displayed in the database window or via code.
MS Access also has a range of additional properties such as Validation Text, which is display when a Validation Rule is broken, and custom properties, that you create yourself through code.
