hi
i have 2 table in my database 
1. MyProducts
productID (code of products)
Salecounter (count of sales)
2. Details
ProductID
Quantity(count of selected product in shoppingcart)
now i want sum Quantity field in the table details . potation to that column "productid" in table "details" include repeater productid
that's means several row of the table maybe has same productid because every shopping cart maybe include that;
then i want set column salecounter in table MyProducts with result of sum query for every productid
how can i do that ?
that's my code but has some error
 //sale counter          string at, sa, bb, kk;         OleDbConnection con = new OleDbConnection(@"provider=microsoft.jet.oledb.4.0;data source=" + Server.MapPath("shop.mdb"));         at = " update myproducts set salecounter = (SELECT sum(details.Quantity) FROM Details Group By ProductID) in(select productid from details);";// WHERE EXISTS (select productid from myproducts)";         OleDbCommand cmm = new OleDbCommand(at, con);      //   OleDbDataReader drm;         con.Open();       //  drm = cmm.ExecuteReader();        // drm.Read();         cmm.ExecuteNonQuery();         con.Close();
          //
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