CODEWITHSUNDEEP
asp.netsqldatabase
Soulblade
Soulblade

Reputation: 71

How to read SQL database specific row text from another row value

I am trying to query data of a specific column text from another column.

Basically, I have a Supplier Database that has a SupplierID and Country column.

I already have the SupplierID for that specific row for example, it is 14. I would like to get the text value of Country column based on the 14 value.

The Supplier ID I am getting by the following code (listbox):

<asp:ListBox ID="SupplierListBox" runat="server" 
            DataSourceID="SupplierCompanyDataSource" DataTextField="Company" 
            DataValueField="SupplierID" Width="315px" 
            Height="80px" 
            onselectedindexchanged="SupplierListBox_SelectedIndexChanged" 
            AutoPostBack="True"></asp:ListBox>

Code: 

        string SupplierListvalue = SupplierListBox.SelectedItem.Value; //SupplierListvalue retrieves the SupplierID value

        SqlDataReader rdr = null;
        SqlConnection conn = new SqlConnection("Data Source=localhost;Initial Catalog=ROG;Integrated Security=True");
        SqlCommand cmd = new SqlCommand("select Country from SupplierDB", conn);
        cmd.Connection = conn;

        conn.Open();
        rdr = cmd.ExecuteReader();
        while (rdr.Read())
        {
            TextBox1.Text = rdr["Country"].ToString();
            MessageBox.Show("Connection Successful");
            MessageBox.Show(rdr.ToString());
        }

        conn.Close();

Upvotes: 0

Views: 1663

Answers (3)

Soulblade
Soulblade

Reputation: 71

I was approaching it in the wrong way. Basically the following was the correct code:

<asp:SqlDataSource ID="SupplierCompanyDataSource" runat="server" ConnectionString="<%$ ConnectionStrings:ROGConnectionString %>"
SelectCommand="SELECT [Company], [SupplierID] FROM [SupplierDB] WHERE ([SupplierID] &gt;= @SupplierID)"> <SelectParameters> <asp:Parameter DefaultValue="14" Name="SupplierID" Type="Int32" /></SelectParameters> </asp:SqlDataSource>

<asp:SqlDataSource ID="SupplierCountryDataSource" runat="server" ConnectionString="<%$ ConnectionStrings:ROGConnectionString %>" SelectCommand="SELECT [SupplierID], [Country] FROM [SupplierDB] WHERE ([SupplierID] = @SupplierID)"> <SelectParameters> <asp:ControlParameter ControlID="SupplierListBox" Name="SupplierID" PropertyName="SelectedValue" Type="Int32" /></SelectParameters></asp:SqlDataSource>

This does the job! So now when I click on the listbox1 the listbox2 also gets clicked similar to cascading.

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460138

Well, it's not clear what's the main problem, so i'll show you a working example which selects the Country column from database with ADO.NET, uses Parameters to avoid SQL-Injection and using-statement to ensure that all unmanaged resources as the connection get disposed(closed).

string sql = @"
            SELECT Country
            FROM dbo.Supplier
            WHERE SupplierID = @SupplierId";
using (var con = new SqlConnection("Data Source=localhost;Initial Catalog=ROG;Integrated Security=True"))
{
    using (var cmd = new SqlCommand(sql, con))
    {
        con.Open();
        cmd.Parameters.Add("@SupplierId", SqlDbType.Int);
        cmd.Parameters["@SupplierId"].Value = int.Parse(SupplierListBox.SelectedItem.Value);
        using (var rdr = cmd.ExecuteReader())
        {
            if (rdr.Read())
            {
                TextBox1.Text = rdr.GetString(0);
            }
        }
    }
}

Upvotes: 2

sgeddes
sgeddes

Reputation: 62841

You need to look into using parameterized queries. Try this out:

    string SupplierListvalue = SupplierListBox.SelectedItem.Value; //SupplierListvalue retrieves the SupplierID value
    ...
    SqlCommand cmd = new SqlCommand("select Country from SupplierDB WHERE SupplierID = @supplierId", conn);
    cmd.Parameters.AddWithValue("@supplierId", SupplierListvalue);
    ...

Good luck.

Upvotes: 0

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