The SqlDataSource.ConflictDetection 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 SqlDataSource.SelectCommand property returns a System.Data.DataTable object with the columns Name and Number and the SqlDataSource.ConflictDetection property is set to the System.Web.UI.ConflictOptions.OverwriteChanges value, parameters are created for Name and Number for the Update method. If the SqlDataSource.ConflictDetection property is set to the System.Web.UI.ConflictOptions.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 SqlDataSource.OldValuesParameterFormatString property.) The System.Web.UI.WebControls.SqlDataSource control then determines if the Update method that is specified in the SqlDataSource.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 SqlDataSource.ConflictDetection property to the System.Web.UI.ConflictOptions.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.

The SqlDataSource.ConflictDetection property delegates to the SqlDataSourceView.ConflictDetection property of the System.Web.UI.WebControls.SqlDataSourceView object that is associated with the System.Web.UI.WebControls.SqlDataSource control.