You can not attach validation controls directly to these Text Boxes.We need to convert these Bound Fields to Template Fields.On the first step of the wizard click on "New Connection" button to open a dialog as shown in Figure 1.

gridviewupdateeventargs rowupdating-17

Now from the smart tag of the Grid View choose "Edit Template" and then select "Edit Item Template" of Company Name column.

This will display the template designer for the column as shown in Figure 6.

On the next step select Customer ID, Company Name, Contact Name and Country columns (Figure 2).

Click on the "Advanced" button and check the "Generate INSERT, UPDATE and DELETE statements" checkbox (Figure 3). Now that you have configured the SQL Data Source control let's bind it with a Grid View control. Open its smart tag and configure it as shown in Figure 4.

Thank you for any insight you can offer in advance.

The Grid View control raises the Row Updating event when a row's Update button is clicked, but before the Grid View control updates the row.

You should see an error message as shown in Figure 7.

This way you can attach client side validation controls to the Grid View columns.

Next, drag and drop a Required Field Validation control below the Text Box.

Set the Control To Validate property of Required Field Validator control to Text Box1 (i.e. Also, set its Error Message property to "Please enter company name".

Note that by default all validation controls validate on the client side.