foreach loop only get last record to gridview c# asp.net

Hi want to fetch data from db using string builder which i am getting from previous page in session . But when o try to bind data i only get last data in the gridview. Please help

Below code is how i get multiple values from checkbox from gridview and pass it to next page using string builder and session.

 SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["connString"].ConnectionString);
            StringBuilder strb = new StringBuilder();
            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                GridViewRow row = GridView1.Rows[i];
                bool isChecked = ((CheckBox)row.FindControl("CheckBox1")).Checked;
                if (isChecked)
                {
                    // strb.Append(GridView1.Rows[i].Cells[7].Text ).AppendLine();
                    strb.Append(GridView1.Rows[i].Cells[7].Text).AppendLine();

                }
                else
                {
                    ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('Please select items to continue');", true);
                }
            }

           // Session["vendor"] = strb.ToString();
            Session["vendor"] = strb.ToString().Trim('n');
            Response.Redirect("order.aspx");
                }
            }

in page 2 i use that session to get values and bind in gridview. The problem is only get last value from the string in foreach loop.

    if (!this.IsPostBack)
            {
                if (Session["vendor"] != null)
                {
                    string[] vendors = Session["vendor"].ToString().Split('n');
                    foreach (string vendor in vendors)
                    {
                        var data = vendor.Trim();
                        
                    SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["connString"].ConnectionString);
 sqlCommand cmd = new SqlCommand("select [Part number],Nomenclature,quantity,[quantity available],[unit price] from Catalouge where [Vendor Code]=('" + data + "')", conn);
                        conn.Open();
                        GridView1.DataSource = cmd.ExecuteReader();
                        GridView1.DataBind();
                    }
                }
            }

Answers:

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Method 1

you are looping through each vendor and overriding the Grid data. Instead, you can get data for all the vendors at a time and bind data to Grid.

Please refer the below logic

if (!this.IsPostBack)
        {
            if (Session["vendor"] != null)
            {
                string[] vendors = Session["vendor"].ToString().Split('n');
                string all_vendors = string.Join("','", vendors).Replace(" ", "");

                SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["connString"].ConnectionString);
                sqlCommand cmd = new SqlCommand("select [Part number],Nomenclature,quantity,[quantity available],[unit price] from Catalouge where [Vendor Code] IN ('" + all_vendors + "')", conn);
                conn.Open();
                GridView1.DataSource = cmd.ExecuteReader();
                GridView1.DataBind();
            }
        }

Method 2

You are binding your grid for each vendor code again and again.

Try this

if (!this.IsPostBack)
{
    if (Session["vendor"] != null)
    {
        string[] vendors = Session["vendor"].ToString().Split('n');
                
        var data = string.Join(", ", vendors.Select(v => $"'{v}'"));

        SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["connString"].ConnectionString);
        sqlCommand cmd = new SqlCommand("select [Part number],Nomenclature,quantity,[quantity available],[unit price] from Catalouge where [Vendor Code] in (" + data + ")", conn);
        conn.Open();
        GridView1.DataSource = cmd.ExecuteReader();
        GridView1.DataBind();
    }
}

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0