Asp net gridview rowupdating event
Also note that by default the Sql Data Source does not perform a Select operation if any of the associated parameters to the Select Command are null.
You can do this by handling an event on the master control to set the parameter value when an item of the master control is data-bound, for example in the Form View Data Bound event. You already seen several examples of data control events in preceding sections of this tutorial.
This is achieved by adding an item to the Drop Down List with an empty string value and setting the Convert Empty String to null property on the associated Control Parameter for the Drop Down List in the data source.
Then in the data source Select Command, you can check for a null value in order to return all (unfiltered) values.
The events that are raised after an operation are used to write custom code to respond to a given operation, or to check the success status of the operation.
For example, you can check the Rows Affected by an Update, Insert, or Delete operation or check the Exception property to determine if an exception occurred during processing.