How to bind data from Database to control fields?

When I select a value in DropDownList, I need to show its corresponding values to the textfields (Of course, there are textfields) from the database.

Example

Database : Table 
eID            eName           eSalary
1              Tincy            50000
2              Vincy            40000

I have a DropDownList specifying the primary key(Here, eID is the prima开发者_如何学运维ry key). So, when I choose a value in DropDownList I need the whole details of eID-1 to be displayed in TextBoxes.

First of all, dropDownList1_SelectedIndexChanged event, handle selected item.

int requestedId = Convert.ToInt32(dropDownList1.selectedItem.Tostring());

and get your results with selectedId

var result = (from s in dataContext.YOURTABLE where s.Id.Equals(requestedId) select s).ToList();
if(result.Count > 0)
{return result.First()}

after First(). you can call any values whatever you want, and bind them to textFields.

To bind data with control follow the below steps:

1.Create stored proceudre or query to fetch data from your database table like

select * from Table where eID = 1

2.query data using DataReader object.

3.Assign value of datareader object to textbox control like

  textbox1.Text = dr["eName "].ToString();