C# data retrieve from database error

Question

i have tried to to load the data to text box, while selecting the drop down list, i was created a class for retrieval and called it in drop down list selected index changed. But i cant get the answer what i want. If i have called the class in Button click event it has worked properly. So please correct me. What i made a mistake. This is what my code:

public void so()
    {
        con.Open();
        string s2;
        s2 = "select Source from tbl_component where Componetcode='" + Mcodeddl.SelectedItem.Text + "'";
        SqlCommand c2 = new SqlCommand(s2, con);
        SqlDataReader d2;
        d2 = c2.ExecuteReader();
        while (d2.Read())
        {
            TextBox1.Text = d2["Source"].ToString().Trim(); 

        }
        d2.Close();
        con.Close();
    }

//i have called the so class here

 protected void Mcodeddl_SelectedIndexChanged(object sender, EventArgs e)
    {
        so();   
    }

there is a typo in the query Componetcode instaed of Componentcode? And then you are subject to query injection — Felice Pollano
– Felice Pollano, Commented Jun 20, 2012 at 7:00
i have created the field in database in the name of Componetcode, that is what a reason i have given like that — user1455232
– user1455232, Commented Jun 20, 2012 at 7:03
Is there any data in 'tbl_component' in database against selected Mcodeddl? — Talha
– Talha, Commented Jun 20, 2012 at 7:05

Habib · Accepted Answer · 2012-06-20 07:13:21Z

2

You should set a breakpoint inside your Mcodeddl_SelectedIndexChanged method to see if the event is triggered, also make sure include AutoPostBack="true" in your dropdownlist definition

edited Jun 20, 2012 at 7:13

Habib

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answered Jun 20, 2012 at 7:07

uowzd01

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1 Comment

user1455232 Over a year ago

thanks. I have forgot to check the Auto post back friend. Thanks again

Habib · Accepted Answer · 2012-06-20 07:02:35Z

1

Make sure you have specified OnSelectedIndexChanged event for the drop down in aspx page

<asp:DropDownList ID="Mcodeddl" runat="server" 
    OnSelectedIndexChanged= "Mcodeddl_SelectedIndexChanged">
</asp:DropDownList>

Also use parameterized SQL queries.

PS. Your SO(); is a method not a class.

answered Jun 20, 2012 at 7:02

Habib

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1 Comment

Habib Over a year ago

@user1455232, post your part of aspx page containing the dropdownlist

user1455232 · Accepted Answer · 2012-06-20 07:12:32Z

1

i have got the answer. And i gave the detail what exactly i have did. "Set AutoPostBack=True"

answered Jun 20, 2012 at 7:12

user1455232

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