how to add table in favourite list in asp.net

Just update the status in your Table. Consider your table contains the below data

-------------------------------------
Name          MiddleName   IsFavorite
-------------------------------------
AAAAAAA       1111111111       Y
BBBBBBB       2222222222       Y
CCCCCCC       3333333333       N
DDDDDDD       4444444444       Y
EEEEEEE       5555555555       N
-------------------------------------

If you want to add a record to favorite list then update.

UPDATE [Table] SET IsFavorite='Y' WHERE [Name]='DDDDDDD'

Use the below query to get favorite list

SELECT * FROM [Table] WHERE IsFavorite='Y'

Using the above query you can pull the data to frontend, then bind it to Gridview or something.

DataTable dt = GetFavoriteList();//Custom function to get data from database
GridFavorites.DataSource = dt;
GridFavorites.DataBind();