c# populate dropdownlist based on dropdownlist in gridview

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

using System.Web.Configuration;

namespace PermacultureOrganizer

{

public partial class OrchardMainWebForm : System.Web.UI.Page

{

//Make the SQL connections

SqlConnection con2 = new SqlConnection(@"Data Source=SQL5018.SmarterASP.net;Initial Catalog=DB_9DE518_Permaculture;Persist Security Info=True;User ID=DB_9DE518_Permaculture_admin;Password=*****");

public string con = WebConfigurationManager.ConnectionStrings["PermaCultureConnection"].ConnectionString;

public void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

//Create EventHandlers

LinkButton btnInsert = new LinkButton();

btnInsert.Click += new EventHandler(btnInsert_Click);

DropDownList ddlTypeName = new DropDownList();

ddlTypeName.SelectedIndexChanged += new EventHandler(ddlTypeName_SelectedIndexChanged);

DropDownList ddlSpecies = new DropDownList();

ddlSpecies.SelectedIndexChanged += new EventHandler(ddlSpecies_SelectedIndexChanged);

DropDownList ddlVariety = new DropDownList();

ddlVariety.SelectedIndexChanged += new EventHandler(ddlVariety_SelectedIndexChanged);

}

}

protected void btnViewData_Click(object sender, EventArgs e)

{

//Go to OrchardViewer Page

Response.Redirect("OrchardViewer.aspx");

}

protected void btnSearchData_Click(object sender, EventArgs e)

{

//Go to OrchardSearch Page

Response.Redirect("OrchardSearch.aspx");

}

protected void ddlTypeName_SelectedIndexChanged(object sender, EventArgs e)

{

//Populate ddlSpecies based on TypeName selection

ddlSpecies.DataSource = RetrieveSpecies(ddlTypeName.SelectedValue);

ddlSpecies.DataBind();

ddlSpecies.Items.Insert(0, "Select Species");

}

private DataTable RetrieveSpecies(string OrchardTypeID)

{

//Use OrchardTypeID from TypeName selection to filter Species

string connString = ConfigurationManager.ConnectionStrings["PermaCultureConnection"].ConnectionString;

string sql = @"SELECT OrchardItemID, OSpecies FROM tblOrchardItem WHERE OrchardTypeID = " + OrchardTypeID;

DataTable dtSpecies = new DataTable();

using (SqlConnection conn = new SqlConnection(connString))

{

conn.Open();

//Initialize command object

using (SqlCommand cmd = new SqlCommand(sql, conn))

{

SqlDataAdapter adapter = new SqlDataAdapter(cmd);

//Fill the result set

adapter.Fill(dtSpecies);

}

}

return dtSpecies;

}

protected void ddlSpecies_SelectedIndexChanged(object sender, EventArgs e)

{

//Populate ddlVariety based on Species selection

ddlVariety.DataSource = RetrieveVariety(ddlSpecies.SelectedValue);

ddlVariety.DataBind();

ddlVariety.Items.Insert(0, "Select Variety");

}

private DataTable RetrieveVariety(string OrchardItemID)

{

//Use OrchardTypeID from Species selection to filter Variety

string connString = ConfigurationManager.ConnectionStrings["PermaCultureConnection"].ConnectionString;

string sql = @"SELECT OrchardItemID, OVariety FROM tblOrchardItem WHERE OrchardItemID = " + OrchardItemID;

DataTable dtVariety = new DataTable();

using (SqlConnection conn = new SqlConnection(connString))

{

conn.Open();

//Initialize command object

using (SqlCommand cmd = new SqlCommand(sql, conn))

{

SqlDataAdapter adapter = new SqlDataAdapter(cmd);

//Fill the result set

adapter.Fill(dtVariety);

}

}

return dtVariety;

}

protected void ddlVariety_SelectedIndexChanged(object sender, EventArgs e)

{

//Gather additional data based on Variety selection

int OrchardItemID = Convert.ToInt32(ddlVariety.SelectedIndex);

BindOrchardGrid(OrchardItemID);

//Display picture next based on Variety selection

string Variety = ddlVariety.SelectedItem.ToString();

switch (Variety)

{

case "Bladen":

imageTree.ImageUrl = "Images/blueberry-vine 300x200.jpg";

break;

case "Bartlett":

imageTree.ImageUrl = "Images/Pear-Tree 300x200.jpg";

break;

case "Babcook":

imageTree.ImageUrl = "Images/peach-tree-w-fruit 300x200.jpg";

break;

case "Abbuoto":

imageTree.ImageUrl = "Images/grape-vine 300x200.jpg";

break;

case "Carya":

imageTree.ImageUrl = "Images/pecans 300x200.jpg";

break;

}

}

private void BindOrchardGrid(int OrchardItemID)

{

DataSet dtLabels;

SqlDataAdapter sda = new SqlDataAdapter();

SqlCommand cmd = new SqlCommand("SELECT * FROM tblOrchardItem WHERE OrchardItemID = " + OrchardItemID, con2);

sda.SelectCommand = cmd;

dtLabels = new DataSet("OrchardItem");

sda.Fill(dtLabels, "OrchardItem");

foreach (DataRow row in dtLabels.Tables["OrchardItem"].Rows)

{

//Gather other pertinent data based on Variety selected

lblTreeSpacing.Text = Convert.ToString(row["OTreeSpacing"]);

lblFertilizingTimes.Text = Convert.ToString(row["OFertilizingTimes"]);

lblPruningTimes.Text = Convert.ToString(row["OPruningTimes"]);

lblWateringNeeds.Text = Convert.ToString(row["OWateringNeeds"]);

lblPollination.Text = Convert.ToString(row["OPollination"]);

int FertilizerID = Convert.ToInt32(row["FertilizerID"]);

int PesticideID = Convert.ToInt32(row["PesticideID"]);

DataSet dtFert;

SqlDataAdapter sdaF = new SqlDataAdapter();

SqlCommand cmdF = new SqlCommand("SELECT * FROM tblFertilizer WHERE FertilizerID = " + FertilizerID, con2);

sdaF.SelectCommand = cmdF;

dtFert = new DataSet("Fert");

sdaF.Fill(dtFert, "Fert");

foreach (DataRow rowF in dtFert.Tables["Fert"].Rows)

{

lblFertilizer.Text = Convert.ToString(rowF["FertilizerName"]);

}

DataSet dtPest;

SqlDataAdapter sdaP = new SqlDataAdapter();

SqlCommand cmdP = new SqlCommand("SELECT * FROM tblPesticide WHERE PesticideID = " + PesticideID, con2);

sdaP.SelectCommand = cmdP;

dtPest = new DataSet("Pest");

sdaP.Fill(dtPest, "Pest");

foreach (DataRow rowP in dtPest.Tables["Pest"].Rows)

{

lblPesticide.Text = Convert.ToString(rowP["PesticideName"]);

}

}

}

public void btnInsert_Click(object sender, EventArgs e)

{

//After the user inputs data, insert it into the database and then switch to OrchardViewer page

CreateOrchard(con);

Response.Redirect("OrchardViewer.aspx");

}

public DataTable CreateOrchard(string con)

{

DataTable dtOrchard = new DataTable();

using (SqlConnection Connection = new SqlConnection(con))

{

SqlCommand sqlcmd = new SqlCommand();

//associate command object with connection

sqlcmd.Connection = Connection;

sqlcmd.CommandType = CommandType.StoredProcedure;

sqlcmd.CommandText = "spInsertOrchardData";

//Gather user input for insert into database

sqlcmd.Parameters.Add("@UserOrchardID", SqlDbType.VarChar, 1000).Value = "";

sqlcmd.Parameters.Add("@TypeName", SqlDbType.VarChar, 1000).Value = Convert.ToString(ddlTypeName.SelectedItem);

sqlcmd.Parameters.Add("@Species", SqlDbType.VarChar, 1000).Value = Convert.ToString(ddlSpecies.SelectedItem);

sqlcmd.Parameters.Add("@Variety", SqlDbType.VarChar, 1000).Value = Convert.ToString(ddlVariety.SelectedItem);

sqlcmd.Parameters.Add("@Age", SqlDbType.Int, 1000).Value = Convert.ToInt32(txtBxAge.Text);

sqlcmd.Parameters.Add("@Yields", SqlDbType.VarChar, 1000).Value = Convert.ToInt32(txtBxYields.Text);

sqlcmd.Parameters.Add("@PlantDate", SqlDbType.VarChar, 1000).Value = Convert.ToString(txtBxPlantDate.Text);

sqlcmd.Parameters.Add("@PlantFrom", SqlDbType.VarChar, 1000).Value = Convert.ToString(txtBxPlantFrom.Text);

sqlcmd.Parameters.Add("@TreeSpacing", SqlDbType.VarChar, 1000).Value = Convert.ToString(lblTreeSpacing.Text);

sqlcmd.Parameters.Add("@FertilizingTimes", SqlDbType.VarChar, 1000).Value = Convert.ToString(lblFertilizingTimes.Text);

sqlcmd.Parameters.Add("@PruningTimes", SqlDbType.VarChar, 1000).Value = Convert.ToString(lblPruningTimes.Text);

sqlcmd.Parameters.Add("@WateringNeeds", SqlDbType.VarChar, 1000).Value = Convert.ToString(lblWateringNeeds.Text);

sqlcmd.Parameters.Add("@Pollination", SqlDbType.VarChar, 1000).Value = Convert.ToString(lblPollination.Text);

sqlcmd.Parameters.Add("@Fertilizer", SqlDbType.VarChar, 1000).Value = Convert.ToString(lblFertilizer.Text);

sqlcmd.Parameters.Add("@Pesticide", SqlDbType.VarChar, 1000).Value = Convert.ToString(lblPesticide.Text);

using (SqlDataAdapter sda = new SqlDataAdapter(sqlcmd))

{

DataSet dataset = new DataSet();

sda.Fill(dataset);

}

}

return dtOrchard;

}

}

}

hi... refer this

 

http://www.aspsnippets.com/Articles/Creating-Cascading-DropDownLists-in-ASP.Net.aspx 

 

https://aspdotnetcodehelp.wordpress.com/2015/04/15/how-to-create-cascading-dropdown-list-in-asp-net/