cascade a dropdown from database in asp.net

Question

I have two databse table 1: Sector 2: Project In Sector table there is 4 sectors(sector1,sector2,sector3,sector4) and if sector1 is selected then then related project shown Sector :: Project ::

Sachin Singh · Answer

@Garima use this protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { ddlsector.DataSource = BindAllSector(); ddlsector.DataTextField = "SectorName"; ddlsector.DataValueField = "SectorID"; ddlsector.DataBind(); ddlsector.Items.Insert(0, new ListItem("Select Sector", "0")); } } protected void ddlsector_SelectedIndexChanged(object sender, EventArgs e) { int sectorId = Convert.ToInt32(ddlsector.SelectedValue); if (sectorId > 0) // If a valid sector is selected { ddlproject.DataSource = BindProjectBySector(sectorId); ddlproject.DataTextField = "ProjectName"; // Display field name ddlproject.DataValueField = "ProjectID"; // Value field name ddlproject.DataBind(); ddlproject.Items.Insert(0, new ListItem("Select Project", "0")); } else { ddlproject.Items.Clear(); ddlproject.Items.Insert(0, new ListItem("Select Project", "0")); } } public DataSet BindProjectBySector(int sectorId) { DataSet ds= new DataSet(); using(SqlConnection con= new SqlConnection("your Connection string")) { SqlDataAdapter da= new SqlDataAdapter("select * from project where sectorid="+sectorId,con); da.Fill(ds); } return ds; } public DataSet BindAllSector() { DataSet ds= new DataSet(); using(SqlConnection con= new SqlConnection("your Connection string")) { SqlDataAdapter da= new SqlDataAdapter("select * from Sector",con); da.Fill(ds); } return ds; }

Naimish Makwana · Answer

Hello Garima, To cascade the dropdown from the database, you can follow these steps: 1. Retrieve the data from the database table "Sector" and bind it to the dropdown "ddlsector". You can do this in the Page_Load event of your code-behind file as follows: protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { ddlsector.DataSource = GetData("SELECT * FROM Sector"); ddlsector.DataTextField = "SectorName"; // Display field name ddlsector.DataValueField = "SectorID"; // Value field name ddlsector.DataBind(); ddlsector.Items.Insert(0, new ListItem("Select Sector", "0")); // Add default item } } Here, "GetData" is a custom function that returns a DataTable containing the data retrieved from the database using the specified SQL query. You can implement this function as per your database connection and query. 2 Handle the SelectedIndexChanged event of "ddlsector" and retrieve the related projects from the database table "Project" and bind them to the dropdown "ddlproject". You can do this as follows: protected void ddlsector_SelectedIndexChanged(object sender, EventArgs e) { int sectorId = Convert.ToInt32(ddlsector.SelectedValue); // Get the selected sector ID if (sectorId > 0) // If a valid sector is selected { ddlproject.DataSource = GetData("SELECT * FROM Project WHERE SectorID = " + sectorId); ddlproject.DataTextField = "ProjectName"; // Display field name ddlproject.DataValueField = "ProjectID"; // Value field name ddlproject.DataBind(); ddlproject.Items.Insert(0, new ListItem("Select Project", "0")); // Add default item } else // If "Select Sector" is selected { ddlproject.Items.Clear(); // Clear the dropdown ddlproject.Items.Insert(0, new ListItem("Select Project", "0")); // Add default item } } Here, "SectorID" and "ProjectID" are assumed to be the primary keys of "Sector" and "Project" tables, respectively, and "SectorID" is a foreign key in the "Project" table referencing the "Sector" table. Also, "ProjectName" and "SectorName" are assumed to be the display field names in the "Project" and "Sector" tables, respectively. Finally, don't forget to add the OnSelectedIndexChanged event handler for "ddlsector" in the markup as follows: Here, AutoPostBack="True" ensures that the page is posted back to the server when the dropdown selection is changed, triggering the SelectedIndexChanged event. Thanks Naimish Makwana

Vishal Yelve · Answer

Please refer below link. https://www.aspsnippets.com/Articles/Creating-Cascading-DropDownLists-in-ASP.Net.aspx

Jignesh Kumar · Answer

Hello Grishma, Please try below url which has step by step explanation for cascade dropdown, https://www.c-sharpcorner.com/UploadFile/009464/cascading-one-dropdownlist-with-other-dropdownlist-in-asp-ne/ https://www.aspsnippets.com/Articles/Populate-Cascading-DropDownList-from-Database-in-ASPNet-Example.aspx

Naimish Makwana · Answer

Hello Garima, The "GetData" method referred to in the code snippet I provided is a custom method that you need to implement yourself. This method is responsible for retrieving data from the database and returning it as a DataTable. Thanks Naimish Makwana

Garima Bansal · Answer

Naimish Makwana I am getting an error in GetData method "The name "GetData" doesnt exists in current context