gridview textbox data edit,validate,update

You can add  the [onUpdating[ event to your gridview, then in that event method you can get the information of the textboxes and validate agains the database, you must have an editIndex which you set inside onEditing function.

 

1.OnEditing event is executed to show the edit template/form of selected row and set the rowIndex..

2.OnUpdating event is executed to do something before saving information into database , here you can validate and prevent submit changes..

 

The link I gave you explains how to do use those two events.

 

 

And to cancel you can use something like this

 

void GridViewCrud_RowUpdating(object sender, GridViewUpdateEventArgs e)  
 {         
   //Here get data from textboxes and validate   

    e.Cancel = true; //this can be use to cancel the update operation or simply do not do the update, it depends of your behaviour
  }  

Hope that helps.