How To Insert Only Unique Data In Database

hello,

i have two datasets. i want to insert all data from one dataset to other.

i am using this:DataSet old = new DataSet();

download dd = new download();old = dd.contactlist("select", "admin", "001");

SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["Project1ConnectionString"].ToString());

try

{string cmd = "select * from contact";

SqlDataAdapter danew = new SqlDataAdapter(cmd, conn);DataSet dsOld = new DataSet();DataSet dsNew = new DataSet();

dsOld = old.Copy();

danew.Fill(dsNew);

 DataTable dtOld = dsOld.Tables[0];DataTable dtNew = dsNew.Tables[0];

 

//int i;foreach (DataRow objRow in dtOld.Rows)

//for(int i=0; i<dtOld.Rows.Count; i++)

{DataRow row;

row = dtNew.NewRow();

 row["company"] = objRow["company"];

row["cust_no"] = objRow["cust-no"];row["sman"] = objRow["sman"];

row["first_name"] = objRow["first-name"];row["contact_title"] = objRow["contact-title"];

row["type"] = objRow["type"];row["contact_loc"] = objRow["contact-loc"];

row["cust_name"] = objRow["cust-name"];row["addr1"] = objRow["addr1"];

row["addr2"] = objRow["addr2"];row["city"] = objRow["city"];

row["state"] = objRow["state"];row["zip"] = objRow["zip"];

row["territory"] = objRow["territory"];row["phone"] = objRow["phone"];

row["fax"] = objRow["fax"];row["extension"] = objRow["extension"];

row["email"] = objRow["email"];row["rec_key"] = objRow["rec_key"];

 

dtNew.Rows.Add(row);

}DataSet nds = dsNew.GetChanges();SqlCommandBuilder bld = new SqlCommandBuilder(danew);

danew.Update(nds);

}

here rec_key is the primary key.

this code works fine but it will insert all data from one dataset to other each time i click a button but i wanted that if data with a rec_key already exists will not insert. only unique values of rec_key will be inserted.

 i am using this code for this:foreach(DataRow rr in dtNew.Rows)

{

if (rr["rec_key"] == objRow["rec_key"])

{

 Response.Write("same");

}

else

{

 dtNew.Rows.Add(row);

}

}

but this doesn't work.

please guide me how can i do this.

thanks