Gets or sets the value indicating how the SqlDataSource control performs updates and deletes when data in a row in the underlying database changes during the time of the operation.
Assembly: System.Web (in System.Web.dll)
The property determines whether parameters for old and new values are applied to the Update method. For example, if the command that is specified by the SelectCommand property returns a DataTable object with the columns Name and Number and the property is set to the OverwriteChanges value, parameters are created for Name and Number for the Update method. If the property is set to the CompareAllValues value, parameters are created for Name, Number, original_Name, and original_Number. (The exact name of the parameters for the original values depends on the OldValuesParameterFormatString property.) The SqlDataSource control then determines if the Update method that is specified in the UpdateCommand property has parameters that match.
Concurrency control is a technique that data stores use to control how data is read and changed in the store when multiple clients are accessing and manipulating the same data. For example, one client reads data and presents it to a user, while another client reads the same data, and presents it to a different user. If both users update the data and submit it to the data storage, some unexpected result might occur, because both clients might update different values for the same data. This is considered a conflict. By setting the property to the CompareAllValues value, your Update method can then compare the old and new values to the original data source to detect conflicts and handle them, as necessary.