insert value from dropdown to table

Question

I try to insert dropdown selected value in table and I am done with this

protected void Button1_Click(object sender, EventArgs e)
{
string Vechile_ID = "";
try
{
Data n = new Data();
tbl_Vechile v = new tbl_Vechile();
v.Vechile_ID = Vechile_ID;
{
v.Vechile_ID = DropDownList1.SelectedValue;
}

n.tbl_Vechile.Add(v).ToString();
n.SaveChanges();

}
catch
{

}
Response.Redirect("Mai.aspx");

}
}

Now the problem is suppose dropdown value are

ERE23
DFG4
ER4

When I select ER4 value then ER4 is inserted in table but when I select again and click on button then value again inserted in table where as I want to insert value only once not wanted to insert same value again and again

How I do this

Amit Gupta · Answer

You have 2 options: 1. Make the column as Primary Key (this doesnot allow user to make duplicate entry) 2. Take a global variable (bool) that determines that your data has been saved or not. Like Bool isSaved; void buttonClicked () { if(!isSaved) // save entry else MesaageBox.Show (Entry already saved); } Do let me know if it solves your problem.

Amit Gupta · Answer

@Gurl When user selects an option from the dropdown and press the save button more than once it will prompt the user that your data has been saved. If you want to check whether any of the option is not to be saved twice then take an array type variable in a session and add the selected item of the dropdown to array... and check its duplicacy on button click if the item is available then prompt the user else allow user to save the entry.

Amit Gupta · Answer

Make some changes in your snippet bool isSaved =false ; try { Data n = new Data(); tbl_Vechile v = new tbl_Vechile(); if (!isSaved) { v.Vechile_ID = Vechile_ID; { v.Vechile_ID = DropDownList1.SelectedValue; } n.tbl_Vechile.Add(v).ToString(); n.SaveChanges(); Session[Vechilevalue] = DropDownList1.SelectedValue; isSaved =true; } } catch { } Response.Redirect(Mai.aspx); //as in asp.net any value of global variable sets its value to its default value. Its better to keep this boolean variable in session. Do let me know if it solves your problem.

scropio gurl · Answer

@ Amit Gupta i try your code suppose there is value in dropdown abc def when i select def and click on button then abc is inserted in table again and again your code is not working properly

scropio gurl · Answer

when i try this .. this shows an error bool isSaved; try { Data n = new Data(); tbl_Vechile v = new tbl_Vechile(); if (!isSaved) v.Vechile_ID = Vechile_ID; { v.Vechile_ID = DropDownList1.SelectedValue; } n.tbl_Vechile.Add(v).ToString(); n.SaveChanges(); Session[Vechilevalue] = DropDownList1.SelectedValue; } catch { } Response.Redirect(Mai.aspx); Error 8 Use of unassigned local variable 'isSaved'