Text Box

praveen_haridas · January 27th, 2006, 04:32 AM

My problem is that I want to retrieve data from database based on some parameters, say some query. Say, I have a table test1

Name Type
car_code varchar2(8)
descript varchar2(50)
rate varchar2(4)

I've a text box called rate which is read-only. I want to display the rate of the car based on the car_code selected. But I dont get how to do this. I'm just a newbie in asp.net and I'm using just the plain asp.net tags. I would be greatful if some one could help me out.

Praveen

praveen_haridas · January 27th, 2006, 07:48 AM

I missed out on one more thing. Suppose the car_code is "CAMXL05" and it's corresponding rate is "65" how can i display the rate for the car_code selected?

Praveen

planoie · January 27th, 2006, 11:04 AM

What do you have so far?

You need to get the date from the database then assign the value to the textbox .Text property.

-Peter

praveen_haridas · January 27th, 2006, 01:05 PM

I'm sorry that I did not state anything about the progress that I've made so far.

Code:

<%@ Import namespace="system.data.oledb"%>
<%@ Import namespace="system.data"%>
<%@ Page Language="vb"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <title>dbtextbox</title>
    </HEAD>
    <body MS_POSITIONING="GridLayout">
        <form id="Form1" method="post" runat="server">
            <asp:TextBox id="dumb" style="Z-INDEX: 100; LEFT: 144px; POSITION: absolute; TOP: 96px" runat="server"
                Width="128px" ReadOnly="True" OnLoad="first_step"></asp:TextBox>
            <asp:dropdownlist id="ddcars" style="Z-INDEX: 101; LEFT: 144px; POSITION: absolute; TOP: 56px" tabIndex="8"
                runat="server" OnLoad="first_step" Width="232px" Height="24px">
                <asp:ListItem></asp:ListItem>
            </asp:dropdownlist>
        </form>
        <script runat="server" language="vb">
            sub first_step(o as object, e as eventargs)
                if not ispostback then
                    dim dtrcars as oledbdatareader
                    dim con as new oledbconnection("Provider=MSDAORA.1;User ID=SCOTT;Password=TIGER;Data Source=HARI")
                    con.open()
                    dim cmd as new oledbcommand("select car_code,descript from car_code",con)
                    dtrcars=cmd.executereader()
                    ddcars.datasource=dtrcars
                    ddcars.datatextfield="descript"
                    ddcars.datavaluefield="car_code"
                    ddcars.databind()
                    dtrcars.close()
                    con.close()
                end if
            end sub

        </script>
    </body>
</HTML>

Well about the progress, I've made not much progress. The only thing is that I've populated the drop down list. But I've to get the rate loaded from the database for the car_code that is being selected from the drop down list. Only then I can proceed further.
Once again thanks in advance.

Praveen

planoie · January 27th, 2006, 09:51 PM

The method you use to do the initial load should be the page_load method. This will be wired automatically for you when you use that name. Then you can use the selectedindexchanged event of the dropdown list to fire off the next step.

-Peter

praveen_haridas · January 28th, 2006, 04:04 AM

Thanks for your answer Peter. But as I've told earlier, since I'm a newbie in this area could you please elaborate on your point a bit more? I mean I did get your point, but that's half understood to me. Well I did try it out but it just doesn't seem to be working or is it my lack of understanding the point that you put forward. Either case I did not understand the whole thing.

Once again thanks in advance.

Regards,

Praveen

planoie · January 28th, 2006, 05:01 AM

You obviously have a grasp on how to get data from the database as is evident by the binding to the dropdown list. How about writing the part that gets data from the DB for the exact thing you need. Don't think about tying in the dropdownlist yet, just write the database access peice of it. Then we can direct you as to how to tie it together. ALso, there are many many tutorials online that can get you started with this kind of task.

-Peter

praveen_haridas · January 28th, 2006, 06:40 AM

As you have suggested I'm including the part that I want exactly with the database access. As of now I've included the code in the query. Later on I'll include the one from the form. The car_code is "CAMXL04" and it's rate is say some 65 or something. But for now this is how it looks.

Code:

<%@ Page Language="vb"%>
<%@ Import namespace="system.data"%>
<%@ Import namespace="system.data.oledb"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <title>dbtextbox</title>
    </HEAD>
    <body MS_POSITIONING="GridLayout">
        <form id="Form1" method="post" runat="server">
            <asp:TextBox id="dumb" style="Z-INDEX: 100; LEFT: 144px; POSITION: absolute; TOP: 96px" runat="server"
                Width="128px" ReadOnly="True"></asp:TextBox>
            <asp:dropdownlist id="ddcars" style="Z-INDEX: 101; LEFT: 144px; POSITION: absolute; TOP: 56px" tabIndex="8"
                runat="server" Width="232px" Height="24px" OnSelectedIndexChanged="rate_capture">
                <asp:ListItem></asp:ListItem>
            </asp:dropdownlist>
        </form>
        <script runat="server" language="vb">
            sub rate_capture(o as object, e as eventargs)
                dim dtrate as oledbdatareader
                dim con1 as new oledbconnection("Provider=MSDAORA.1;User ID=SCOTT;Password=TIGER;Data Source=HARI")
                con1.open()
                dim cmd1 as new oledbcommand("select rate from car_code where car_code='CAMXL04'",con1)
                dtrate=cmd1.executereader()
                dtrate.close()
                    con1.close()
            end sub
        </script>
    </body>
</HTML>

I'm not pretty much sure about what to do after the query. This is because I've no idea of how to do it. And for the tutorials, I've looked for it everywhere. I could not site one that was suiting my requirements, though there were some but it was all coded in different languages. As I'm only used to the server script I could not find one that was done in server scripts. If you could suggest any tutorials that is suitable for beginners like me I would be greatful.

Thanks in advance.

Regards

Praveen

praveen_haridas · January 30th, 2006, 02:41 AM

Can anyone please help me out with the above topic

Thanks in advance

Regards

Praveen

praveen_haridas · January 31st, 2006, 02:35 PM

Hi everyone,
I found a way out to my problem through hours and hours of browsing in the net. But the method that I found is also proving to be an utter failure. Can anyone help me in this? The following is the code that I made up by going through a PDF file.

Code:

<%@ Import namespace="system.data.oledb"%>
<%@ Import namespace="system.data"%>
<%@ Page Language="vb"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <title>dbtextbox</title>
        <meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
        <meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
        <meta name="vs_defaultClientScript" content="JavaScript">
        <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
    </HEAD>
    <body MS_POSITIONING="GridLayout">
        <form id="Form1" method="post" runat="server">
            <asp:TextBox id="dumb" style="Z-INDEX: 100; LEFT: 144px; POSITION: absolute; TOP: 96px" runat="server"
                Width="128px" ReadOnly="True"></asp:TextBox>

<script runat="server" language="vb">
sub rate_capture(o as object, e as eventargs)
         dim dtrate as oledbdatareader
         dim con1 as new oledbconnection("Provider=MSDAORA.1;User ID=SCOTT;Password=TIGER;Data Source=HARI")
         con1.open()
         dim cmd1 as new oledbcommand("select rate from car_code where car_code='CAMXL04'",con1)
         dtrate=cmd1.executereader()
         dtrate.close()
         con1.close()
'****The following code is what I got after referring to the document.
         dumb.Text = String.Empty
        If dtrate.Read() Then
            Dim currentValue As Object = dtrate("rate")
                If currentValue <> System.DBNull.Value Then 
                        dumb.Text = currentValue.ToString().Trim()
                    End If
            End If
    end sub
        </script>
    </body>
</HTML>

In spite of adding this code, my requirements are still not met. I dont get the exact reason of it not working. Could any one suggest me a way out. When I compile the above code I get the following error and I did not understand what exactly does it imply.

BC31080: Operator '<>' is not defined for types 'System.Object' and 'System.DBNull'. Use 'Is' operator to compare two reference types.

I would be greatful if some one could help me out of this problem.

Thanks in advance

Regards

Praveen

Praveen