在ASP.NET Web表单中使用SQL Server在一个表中使用两个外键

Question

I've created BidTable in which I've used two foreign keys ie ID from Reg table & CarID from SubmitAdd table.

ID from Reg table is fetched by comparison of username with current session's username while CarID is fetched by comparing query string ID with CarID .

The problem is when I use both of them in BidTable as foreign keys, BidTable can not fetch both of their data. But when I use them separately, for example I use only ID from Reg in BidTable as a foreign key, it works perfectly.

Here's the code:

string cs = ConfigurationManager.ConnectionStrings["CONN"].ConnectionString;

using (SqlConnection con = new SqlConnection(cs))
{
    SqlCommand cmdd2 = new SqlCommand("select * from SubmitAdd where CarID='"+ Request.QueryString["id"].ToString() + "'", con);//taking CarID from QueryString
    con.Open();

    SqlDataAdapter sdda = new SqlDataAdapter(cmdd2);
    DataTable dtt = new DataTable();
    sdda.Fill(dtt);

    SqlCommand cmdd = new SqlCommand("select * from Reg where username='"+ Session["USERNAME"] + "'", con);

    SqlDataAdapter sda = new SqlDataAdapter(cmdd);
    DataTable dt = new DataTable();
    sda.Fill(dt);       

    if (dtt.Rows.Count != 0 && dt.Rows.Count != 0)
    {
        int id = Convert.ToInt32(dt.Rows[0][0]); // Get Registration ID from Reg Table
        int CarID = Convert.ToInt32(dtt.Rows[0][0]);// Get CarID from SubmitAdd Table

        string ss = "insert into BidTable values('" + id + "','" + CarID + "','" + TextBid.Text + "')";

        SqlCommand cmd = new SqlCommand(ss, con);

        SqlDataAdapter sda2 = new SqlDataAdapter(cmd);
        DataTable dt2 = new DataTable();
        sda2.Fill(dt2);
    }
}

Answer 1

Please check join while fetching records, if you dont have either category id or userid and if you are using inner join then records will be ommited. Use left join.