How to Populate a Dropdownlist from a Database

What is the right way to populate a DropDownList from a database?

You could bind the DropDownList to a data source (DataTable, List, DataSet, SqlDataSource, etc).

For example, if you wanted to use a DataTable:

ddlSubject.DataSource = subjectsTable;
ddlSubject.DataTextField = "SubjectNamne";
ddlSubject.DataValueField = "SubjectID";
ddlSubject.DataBind();

EDIT - More complete example

private void LoadSubjects()
{

    DataTable subjects = new DataTable();

    using (SqlConnection con = new SqlConnection(connectionString))
    {

        try
        {
            SqlDataAdapter adapter = new SqlDataAdapter("SELECT SubjectID, SubjectName FROM Students.dbo.Subjects", con);
            adapter.Fill(subjects);

            ddlSubject.DataSource = subjects;
            ddlSubject.DataTextField = "SubjectNamne";
            ddlSubject.DataValueField = "SubjectID";
            ddlSubject.DataBind();
        }
        catch (Exception ex)
        {
            // Handle the error
        }

    }

    // Add the initial item - you can add this even if the options from the
    // db were not successfully loaded
    ddlSubject.Items.Insert(0, new ListItem("<Select Subject>", "0"));

}

To set an initial value via the markup, rather than code-behind, specify the option(s) and set the AppendDataBoundItems attribute to true:

<asp:DropDownList ID="ddlSubject" runat="server" AppendDataBoundItems="true">
    <asp:ListItem Text="<Select Subject>" Value="0" />
</asp:DropDownList>

You could then bind the DropDownList to a DataSource in the code-behind (just remember to remove:

ddlSubject.Items.Insert(0, new ListItem("<Select Subject>", "0"));

from the code-behind, or you'll have two "" items.

What is the way to populate a dropdownlist from a database in asp.net by using classes?

This line of code in your getNationalitymethod...

comm = new SqlCommand("spGetAllUsers", conn);

...should be this instead

comm = new SqlCommand("spGetNationalities", conn);

Databinding should work if your Nationality table has columns ID and Nationality

How to populate HTML dropdown list with values from database

My guess is that you have a problem since you don't close your select-tag after the loop. Could that do the trick?

<select name="owner">
<?php 
$sql = mysqli_query($connection, "SELECT username FROM users");
while ($row = $sql->fetch_assoc()){
echo "<option value=\"owner1\">" . $row['username'] . "</option>";
}
?>
</select>

New to MVC, Populating a DropDownList from a database

Finally figured it out. used ViewBag to populate the dropdown.

First add the database you need to your controller:

private MyDataBase db = new MyDataBase();

Then set a ViewBag as a new SelectList in the controller:

ViewBag.MyViewBagVariable = new SelectList(db.MyDataBaseModels, "ID", "ID");

And finally, under the View use the DropDownListFor helper with your ViewBag to populate the dropdown list:

@Html.DropDownListFor(model => model.MyDataBaseValue, (SelectList)ViewBag.MyViewBagVariable

How To Populate a DropDown List From a DataSet?

In order to show the data in the DropDownList control, you can use the following Code. To use the results of a Stored Procedure, you need to create the SELECT command:

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
        Dim dt As New DataTable
        Dim connString As String = "Server=MYCOMPUTER\SQLEXPRESS;Database=scales;Trusted_Connection=True"
        Using myConn As New SqlConnection(connString)
            myConn.Open()
            Using cmd = myConn.CreateCommand()
                cmd.CommandType = CommandType.StoredProcedure
                cmd.CommandText = "dbo.uspMyStoredProc"
                cmd.Parameters.AddWithValue("@MyInputParam", 123)
                Using da As New SqlDataAdapter(cmd)
                    da.Fill(dt)
                End Using
            End Using
        End Using
        ComboBox1.DisplayMember = "scaleName"
        ComboBox1.DataSource = dt
        ComboBox1.DataBind()
    End If
    ' ...
End Sub

I've adjusted the following things:

• Usually you only need to bind the data on the initial request. Therefore, the if statement at the beginning checks the IsPostBack property.
• In order to close and dispose the connection and the data datapter reliably, I've added some using statements.
• In order to access the stored procedure, I've created a SqlCommand and set the CommandType to StoredProcedure. The CommandText is set to the name of the Stored Procedure. In the sample, I've also added a parameter named MyInputParam that is sent to the Stored Procedure.

Populate DropDownList in ASP.NET MVC from database table using Entity Framework 6 and ViewModel

The main issue is that in the view you have new SelectList(Model.Grades, "ID", "Level") but Grades is IEnumerable<SelectListItem> and SelectListItem does not contain properties named ID and Level.

However there are a a few other issues with your code. First a view model should not contain a data model, and instead your view model should be

public class GradeSelectListViewModel
{
    public int? ID { get; set; } // make this ID so you do not need an input for it
    public string Name { get; set; }
    .... // other properties of Employee that your editing
    [Required(ErrorMessage = "..")]
    public int? Level { get; set; } // make value types nullable to protect against under-posting attacks
    public IEnumerable<SelectListItem> Grades { get; set; }
}

and add display and validation attributes as required. Note that I deleted the constructor (you don't seem to be using it, but if you did, then you also need to include a parameter-less constructor, otherwise an exception will be thrown when submitting to the POST method. I also assume that Level should be typeof int since you binding to the int ID property of Grade.

The the code in your GET method should be

Employee employee = db.Employees.Find(id);
var model = new GradeSelectListViewModel()
{
    ID = employee.EmployeeID,
    Name = employee.Name,
    Level = employee.Level, // convert to int?
    ....
    Grades = db.Grades.Select(x => new SelectListItem
    {
        Value = x.ID.ToString(),
        Text = x.Level
    })
};
return View(model);

and in the view

 @Html.DropDownListFor(x => Model.Level, Model.Grades, "Select Level")

Note also that in the POST method, your need to reassign the SelectList if you return the view because ModelState is invalid.

How to populate a dropdown from database table using MVC?

Add the List to your model:

public List<string> DropDownList= new List<string>();

and then in your model create a function to load the data for the DropDownList from the database:

public void GetDropDownList()
{

//Pass your data base connection string here 
using (SqlConnection c = new SqlConnection(cString))
//Pass your SQL Query and above created SqlConnection object  "c"
using (SqlCommand cmd = new SqlCommand("SELECT Column1 FROM Table", c))
{
    using (SqlDataReader rdr = cmd.ExecuteReader())
    {
        while (rdr.Read())
        {

         DropDownList.Add(rdr["Column1"].ToString())

        }
    }
}
}

and then in Controller finally, you need to send your model to the view:

//Create object of your Model of controller
 Model objModel = new Model();
 //Call function to  load the data for the DropDownList
 objModel.GetDropDownList();
 //return view with your object of model
 return View(objModel);

Now in the Razor you can display this:

    @Html.DropDownListFor(m => Model.DropDownList);

How to populate a html dropdown dynamically with values from a postgres database?

In the backend (flask) you can fetch all the values from the Postgres database using the query:

# code to connect to db
...
# code to fetch from database
list_of_regions = db.execute("select region_name from regions")

Then pass on those values to the front end page:

@app.route("/")
def index():
    return render_template("index.html", list_of_regions = list_of_regions)

On the front end you can loop through the values with Jinja and add the items to the dropdown:

<label for="regions">Choose a region:</label>

<select name="regions" id="regions">
  {% for region in list_of_regions %}
    <option value={{region.lower()}}>{{region}}</option>
  {% endfor %}
</select>

Just replace your case-specific code with the general code that is provided above and it should be good to go. I was not sure about how to connect to postgres database as I have worked mostly with MySQL, so I guess this package might help you out better for that.

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