Update in ASP.NET results in an exception: “must declare scalar variable”

I am trying to update a certain record in my Student table, however the same exception keeps popping up as such:

System.Data.SqlClient.SqlException: Must declare the scalar variable “@sid”

Please do give any suggestions as I can’t seem to find any error with my code.

This is the code for my update query:

if (conn.State == System.Data.ConnectionState.Closed)
{
    conn.Open();

    String sid = txtSearch.Text;

    SqlCommand cmd2 = new SqlCommand("UPDATE [Student] SET [Password] = @pass, [StudentName] = @studName, [Email] = @email, [PhoneNumber] = @number, [Faculty] = @faculty, [Course] = @course WHERE [StudentID] = @sid", conn); 

    cmd2.Parameters.AddWithValue("@pass", txtPassword.Text);
    cmd2.Parameters.AddWithValue("@studName", txtStudentName.Text);
    cmd2.Parameters.AddWithValue("@email", txtEmail.Text);
    cmd2.Parameters.AddWithValue("@number", txtPhoneNum.Text);
    cmd2.Parameters.AddWithValue("@faculty", ddlFaculty.SelectedValue);
    cmd2.Parameters.AddWithValue("@course", ddlCourse.SelectedValue);

    cmd2.ExecuteNonQuery(); 

    Response.Write("<script>alert('Record updated successfully!')</script>");
    conn.Close();

    Clear();
}

Answers:

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Method 1

you missed out @sid param

    if (conn.State == System.Data.ConnectionState.Closed)
    {
        conn.Open();

        String sid = txtSearch.Text;
        SqlCommand cmd2 = new SqlCommand("UPDATE [Student] SET [Password]<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="a39ee3d3c2d0d0">[email protected]</a>
            , [StudentName]<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="6f522f1c1b1a0b210e020a">[email protected]</a>
            , [Email]<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="526f12373f333b3e">[email protected]</a>
            , [PhoneNumber]<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="af92efc1dac2cdcadd">[email protected]</a>
            , [Faculty]<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="5c611c3a3d3f29302825">[email protected]</a>
            , [Course]<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="8cb1ccefe3f9feffe9">[email protected]</a> 
        WHERE [StudentID]<a href="https://getridbug.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="85b8c5f6ece1">[email protected]</a>", conn); 
        cmd2.Parameters.AddWithValue("@pass", txtPassword.Text);
        cmd2.Parameters.AddWithValue("@studName", txtStudentName.Text);
        cmd2.Parameters.AddWithValue("@email", txtEmail.Text);
        cmd2.Parameters.AddWithValue("@number", txtPhoneNum.Text);
        cmd2.Parameters.AddWithValue("@faculty", ddlFaculty.SelectedValue);
        cmd2.Parameters.AddWithValue("@course", ddlCourse.SelectedValue);
        cmd2.Parameters.AddWithValue("@isid", sid);     // <------
        cmd2.ExecuteNonQuery(); 

        Response.Write("<script>alert('Record updated successfully!')</script>");
        conn.Close();

        Clear();
    }

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