when gridView update is fired?

I asked a question Gridview is not displayed when using stored procedure in SQLDatasource which I want to resolve . Based on my old question, I am not sure when exactly is gridView update fired. I am under the impression

• Gridview Update is fired automatically when the page is loaded if you use SQL Statement in SQLDatasource

• GridView needs to be manually bound using sqldatasource.databind() fun开发者_高级运维ction to update data if you use stored procedure.

But even then, the second case is not working for me. I know this implementation is somewhat buggy.Can anyone guide me throw this, when exactly Gridview is updated and possibly throw some light on my original question also?

Thanks!

Update: After further research, I found that databind() property is not needed to update the gridView. What is needed is a post-back. So if you add a button with no code inside it, it will update the gridView simply because the page has been reposted and (maybe)the textfield values have changed too.

I still dont get any result though. What I have done is entered "not data found" in empty template for the gridview. So now I get "Data not found" instead of nothing. Which does means that SP is run but returns 0 result.

Another thing that I found is, if you bound a text field to the SQLDataSource, by default, it changes the empty textbox value to NULL. This is kind of stupid, why will you need the NULL values for? This will result in 0 records since obviosly we dont store null int the database. (Null means nothing but Microsoft though the other way). So to fix that, go to the parameters list in SQL Datasource and select the parameter. Click on the link "Show advance properties" There change the property "ConvertEmptyStringToNull" from true to false. Although it did not fixed my problem yet (but fixed it somewhere else).

I am thinking I am using 4 parameters in sqlprocedure and one of them is causing problem? But the query does not ok when testing in SQLDatasource.

Is there a reason why you must use the GridView update event? Why not just add the code to bind the GridView during the Page_Load event or something? Have you at least tried to narrow down the causes for the erroneous behavior?

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
         SqlDataSource1.DataBind();
    }
}

After my research, I found GridView is automatically updated when the page loads. It is the same weather an SQL Statement or a Stored Procedure is used in SQLDataSource. Also SDQDatasource.Databind() is not needed, but may be needed in special scenarios.

What triggers GridView update is page load. If you create a button and add a click event, just clicking that button will automatically cause gridview to update but clickevent cause page reload.

Hope it helps