help me identify the bug in my code

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hi i am giving small downgraded version of my code but please help me to identify the bug.a detailed explanation would be help full.what i am doing is i am storing selected value from a drop down list into an variable . now when i click button the value in variable must get stored in database but what is happening that when i click on button i get this error

The parameterized query '(@value nvarchar(4000))insert into abs2(vab2)values(@value)' expects the parameter '@value', which was not supplied.

when i debug i found value of variable to be always null can anybody tell me whats happening

here is my code.please tell where i went wrong and what should i do and why ithappens?
first markup

HTML

<html xmlns="http://www.w3.org/1999/xhtml">
<head  runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1"  runat="server">
    <div>
      <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" 
       onselectedindexchanged="DropDownList1_SelectedIndexChanged" Width="112px">
            <asp:ListItem>value1</asp:ListItem>
            <asp:ListItem>value2</asp:ListItem>
            <asp:ListItem>value3</asp:ListItem>
            <asp:ListItem>value4</asp:ListItem>
        </asp:DropDownList>
    <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
      </div>
    </form>
</body>
</html>

C#

public partial class _Default : System.Web.UI.Page
{
    string var;
    SqlConnection conn;
    SqlCommand cmd;
    string str = ConfigurationManager.ConnectionStrings["cnstr"].ConnectionString;
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        var = DropDownList1.SelectedValue;
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        conn = new SqlConnection(str);
        cmd = new SqlCommand("insert into abs2(vab2)values(@value)",conn);
        cmd.Parameters.AddWithValue("@value", var);
        try
        {
            conn.Open();
            int a = cmd.ExecuteNonQuery();
            if (a > 0)
            {
                Response.Write("inserted");
            }
            else
            {
                Response.Write("failed");
            }
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
        finally
        {
            conn.Close();
        }
    }
}

Posted 2-Jan-12 20:07pm

anoop_vip

Updated 2-Jan-12 20:10pm

Mehdi Gholam

v2

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devbtl · Answer 1 · 2012-01-02T20:27:00

Solution 1

SQL

cmd = new SqlCommand("insert into abs2(vab2)values(@vab2)",conn);
cmd.Parameters.AddWithValue("@value", var);

you can insert direct by passing var to query

Posted 2-Jan-12 20:27pm

devbtl

Updated 2-Jan-12 20:28pm

v2

Anupam Singh · Answer 2 · 2012-01-02T21:07:00

Solution 2

declare variable like

C#

var v= DropDownList1.SelectedValue;

cmd=new SqlCommand("insert into abs2(vab2)values(@vab2)",conn);
cmd.Parameters.AddWithValue("@value", v);

Posted 2-Jan-12 21:07pm

Anupam Singh

Updated 3-Jan-12 10:29am

v2

shek124 · Answer 3 · 2012-01-03T20:33:00

Solution 3

Try this one

SQL

cmd = new SqlCommand("insert into abs2(vab2)values(@value)",conn);
cmd.Parameters.AddWithValue("@value", DropDownList1.SelectedValue);

Posted 3-Jan-12 20:33pm

shek124

phil.o · Answer 4 · 2012-01-03T22:05:00

Solution 4

string var;

You cannot use var as variable name ; var is a reserved word.

Posted 3-Jan-12 22:05pm

phil.o

Vinod Satapara · Answer 5 · 2012-01-03T22:12:00

VALUE is reserved key word. Please use any other variable name

http://msdn.microsoft.com/en-us/library/aa238507(v=sql.80).aspx[^]

C#

conn = new SqlConnection(str);
cmd = new SqlCommand("insert into abs2(vab2)values(@value1)",conn);
cmd.Parameters.AddWithValue("@value1", var);

Thanks
Vinod