Populate the textbox from a dropdownlist

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i have 2 dropdownlist and one textbox.for this i have a table named mrp which contain three fields(MRP,ITEM, RATE). the first dropdownlist i populated with MRP. whichever MRP is selected ,on the basis of that MRP's items the second dropdownlist will populate. now on the selection of the items from the second dropdownlist the rate of the items should be shown in the textbox.
i have done populating both the dropdown. can anyone tell me how i populate the textbox with rate of the selected item in the second dropdownlist. i want the answer in c#

What I have tried:

C#

protected void Page_Load(object sender, EventArgs e)
{
  if (!Page.IsPostBack) 
  { 
    SqlConnection con = new SqlConnection("Data Source=MICKEY\\SQLEXPRESS;Initial Catalog=rr;Integrated Security=True");
    SqlCommand com = new SqlCommand("select distinct MRP from mrp");
    // SqlDataReader sdr;
    DataSet ds = new DataSet();
    SqlDataAdapter da = new SqlDataAdapter(com.CommandText, con);
    con.Open();
    da.Fill(ds,"mrp");
    ddlmrp.DataSource = ds.Tables[0];
    ddlmrp.DataTextField = ds.Tables[0].Columns["MRP"].ColumnName;
    ddlmrp.DataValueField = ds.Tables[0].Columns["MRP"].ColumnName;
    ddlmrp.DataBind();
    //ddlmrp.SelectedValue = 0;

    //ddlmrp.Items.Insert(0, new ListItem("--Select--", "0"));
   }
}

protected void ddlmrp_SelectedIndexChanged(object sender, EventArgs e)
{
  SqlConnection con = new SqlConnection("Data Source=MICKEY\\SQLEXPRESS;Initial Catalog=rr;Integrated Security=True");
  SqlCommand com = new SqlCommand("select ITEM from mrp where mrp = '"+ddlmrp.SelectedValue.ToString()+"'", con);
  // SqlDataReader sdr= new SqlDataReader();
  DataSet ds = new DataSet();
  SqlDataAdapter da = new SqlDataAdapter(com);
  con.Open();
  if (ds.Tables.Contains("mrp"))
  {
    ds.Tables[0].Reset();
  }
  da.Fill(ds, "mrp");
  ddlitems.DataSource = ds.Tables[0];
  ddlitems.DataTextField = ds.Tables[0].Columns["ITEM"].ColumnName;
  ddlitems.DataValueField = ds.Tables[0].Columns["ITEM"].ColumnName;
  ddlitems.DataBind();

  //TextBox1.Text = sdr["select RATE FROM mrp where ITEM ='"+ddlitems.SelectedValue.ToString()+"'",con].ToString();

  con.Close();
}

Posted 3-Mar-16 23:14pm

Member 12355460

Updated 4-Mar-16 0:09am

VR Karthikeyan

v2

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Comments

Richard Deeming 4-Mar-16 6:00am

Your code is vulnerable to SQL Injection[^].

NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

Member 12355460 5-Mar-16 0:42am

how

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VR Karthikeyan · Accepted Answer · 2016-03-04T00:09:00

Use selection changed event for item dropdownlist, and get the selected item id when item dropdown list changing, use this id to pass with sql to get the rate of the corresponding item.

C#

protected void ddlitems_SelectedIndexChanged(object sender, EventArgs e)
{
  ListItem objItem = ddlitems.SelectedItem;
  string selectedItemId = objItem.Text;
  SqlConnection con = new SqlConnection("Data Source=MICKEY\\SQLEXPRESS;Initial Catalog=rr;Integrated Security=True");
  SqlCommand com = new SqlCommand("select RATE from mrp where item = '" +  selectedItemId + "'", con);
  DataTable PriceTable = new DataTable();
  SqlDataAdapter da = new SqlDataAdapter(com);
  con.Open();
  da.Fill(PriceTable);
  con.Close();

  TextBox1.Text = PriceTable.Rows[0][0].ToString().Trim();
}