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That is what the code I gave you does. It sends the query to the database and retrieves the result. Here is again, but annotated more fully.
OleDbConnection myConnection = new OleDbConnection(myConnectionString);
myConnection.Open();
OleDbCommand cmd = new OleDbCommand(myConnection,
"SELECT id, dataColumn1, dataColumn2, etc FROM myTable WHERE id = ?");
cmd.Parameters.Add(id);
OleDbDataReader reader = cmd.ExecuteReader();
int id = reader.GetInt32(0);
string myValue = reaser.GetString(1);
myConnection.Close();
Also, the MSDN documentation will explain each of these classes and methods with further examples.
* DISCLAIMER: I typed this by hand without running it through a compiler. There may be some small errors.
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oh thanks so much for a more detailed description! it's more clear to me what those codes mean now. =)
but what i meant was what actually are the steps to send a query to my database? what am i supposed to click on to enter those codes that you have shown me?
>sorry im new to database stuff and i really need some help in making things work.. and seriously, i learn better this way, through step by step guidance and hands-on experience.. nevertheless, i'll be reading up on the relevant links that may be helpful..
thanks again! =)
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nidhelp wrote:
but what i meant was what actually are the steps to send a query to my database?
The steps are those I've shown you above.
nidhelp wrote:
what am i supposed to click on to enter those codes that you have shown me?
Umm... The text editor. Then you start typing. (I know that sounds a stupid answer, but there is nothing to click on. No magic buttons to press. You really have to do the work).
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SORRY im still stuck...i cant figure out where to type the codes. which section of my program should i type?
THANKS!
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There are many ways to do this. One of the correct ways is to create a DAL (Data Abstraction Layer) in your application. This is really just a class, or set of classes (if your application is big) that communicates with the database for you. It then returns the data to what ever part of the application needed it.
e.g.
class Dal
{
private string connectionString;
public Dal()
{
connectionString = ConfigurationSettings.AppSettings["connectionString"];
}
private SqlConnection Connection
{
get
{
return new SqlConnection(connectionString);
}
}
public Hashtable GetMyData()
{
Hashtable result = new Hashtable();
for(int i=0; i<myDataReader.FieldCount;i++)
{
string columnName = myDataReader.GetName(i);
object columnValue = myDataReader.GetObject(i);
result[columnName] = columnValue;
}
return result
}
}
Then somewhere in the code that needs the data from the database you can write something like this:
Dal dal = new Dal();
Hashtable data = dal.GetMyData();
Does this help?
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Hey! I've done something similar to this and i know just how you feel. My suggestion is that you separate your queries (data gathering from database) from you UI form. Create another form which would contain your connection string as well as all your queries then pass it to your main form.
Try this:
public class DS_Company<br />
{<br />
OdbcConnection conn = new OdbcConnection("ConnectionString");<br />
string strSQL;<br />
<br />
public DS_Company()<br />
{<br />
conn.Open();
}<br />
<br />
public DataSet GetID(string strID)<br />
{<br />
strSQL = " SELECT ";
strSQL += " * ";
strSQL += " FROM Table";
strSQL += " WHERE IDnumber='"+ strID +"'";
<br />
DataSet ds = new DataSet();
OdbcDataAdapter adpDS = new OdbcDataAdapter(strSQL,conn); <br />
adpDS.Fill(ds);
return ds;
}<br />
}<code><br />
<br />
hope that helps <br />
<br />
Kampai!!!
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Well to tell you the truth im a beginner too but i'l try my best to be of assistance. Go ahead and post your code or better yet email me your form. I'l see what i can cook-up
Kampai!!!
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OH YES!!!!!!! I managed to solve it already!
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oh no! my problem's not solved yet...
im doing parameterised query. i managed to load my data and correctly inside the textbox controls which are placed on the same page as where i've placed my textbox and Go button.
if this is not clear, i mean i managed to do this> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbwlkwalkthroughdisplayingdatainwindowsformusingparameterizedquery.asp
however, what i want to do is, the user types a criterior in the textbox and press the Go button which are in form1. the Go button sends query to Access db and loads the data inside the textbox controls in form2.
thanks
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HI
Im trying to create a c#.net windows form program that keeps track of a series of sports results. I want to be able to enter all the teams into a list box at the start of the program and then store this information in a Dataset. This Dataset is then saved as an xml file. After the program has been restarted i want the listbox to be populated with the data saved in the xml file.
Am I able to bind the listbox to a table in the dataset? If so how do i load data for the next entry in the listbox and so on?
thanks
Rich
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HI
Im trying to create a program that keeps track of a series of sports results. I want to be able to enter all the teams into a list box at the start of the program and then store this information in a Dataset. This Dataset is then saved as an xml file. After the program has been restarted i want the listbox to be populated with the data saved in the xml file.
Am I able to bind the listbox to a table in the dataset? If so how do i load data for the next entry in the listbox and so on?
thanks
Rich
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I know there are so many question regarding this NullReferenceException...
but still i couldn't find any solution for my prob...
i've got a runtime error...
it says that...
"An unhandled exception of type 'System.NullReferenceException' occurred in OraGraphing.exe
Additional information: Object reference not set to an instance of an object."
this is my code... the error is at price...
<br />
public int counter;<br />
public sting[] price;<br />
<br />
private void Form1_Load(object sender, System.EventArgs e)<br />
{<br />
OracleConnection oraConn = new OracleConnection("Data Source=quotes; user id=me; password=you;");<br />
OracleCommand oraCmd = new OracleCommand("SELECT isin, to_char(trading_date,'dd/mm/yy hh24:mi:ss'), last_done_price FROM realtime_tracking",oraConn);<br />
oraConn.Open();<br />
OracleDataReader oraDR = oraCmd.ExecuteReader();<br />
<br />
counter = 0;<br />
while(oraDR.Read())<br />
{ <br />
try<br />
{<br />
price[counter] = oraDR["last_done_price"].ToString();
}<br />
catch (NullReferenceException nre)<br />
{<br />
MessageBox.Show(nre.Message);<br />
}<br />
counter++;<br />
};<br />
<br />
oraDR.Close();<br />
oraConn.Close();<br />
}<br />
I think that error because of i didnt declare how large the array is... but how? since i didnt know how large is the data inside that database...
-----------------------------------------------
=^_^= I'm a noob whose trying to learn... =^_^=
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yup..
its true.. when i put how many elements.. it runs correctly..
but.. i want to make it dynamically,
since the data in the database keeps updating/increasing/decreasing..
so.. basically i dont know the number of elements..
------------------------------------------------------
=^_^= Thank you to those who answer my question =^_^=
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Use a list instead of an array, like an ArrayList, then you don't have to know the number of items to create it.
---
b { font-weight: normal; }
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<br />
price = new string[oraDR.Count]; <br />
while(oraDR.Read())<br />
{ <br />
try<br />
{<br />
price[counter] = oraDR["last_done_price"].ToString();
}<br />
catch (NullReferenceException nre)<br />
{<br />
MessageBox.Show(nre.Message);<br />
}<br />
No hurries, no worries.
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sorry 'bout themany replies, CP was working against me
No hurries, no worries.
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I want to Enumerate Users on Remote Machine with username and password. I am using NetEnumUser function in (Advapi32.dll)/ this function enumerates user with windows 2000 but when runs on windows xp it returns access denied. I am searching for a function that will authenticate my credentials and get the remote machine users.
Thanks in Advance
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hello friends,
i am developing an application, which needs to transfer the data from one computer to another with the help of socket programming.
i want to make the server in the listening mode on port 80, so that whenever client send the connection request, it will be connected on port 80.
please tell me whether it is possible or not to put the application on the listening mode on port 80.
i tried it using system.net namespaces's SocketObj.Bind method using port 80 but it gives the error that
"Only one usage of each socket address (protocol/network address/port) is normally permitted".
this will work fine for other ports. but for other ports i have the problem that may be that port will be blocked by the company where this project is implemented.
please help me anyway if u can!
Thanks to all and codeproject too.
Gagan Deep Singla
Chandigarh - INDIA
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Hi!
The error message you get is correct. A port can be assigned to a single application only.
In your case, a webserver will be listening on port 80 (because this is the regular port for web requests) when your application starts.
Either choose a different port (those above 1024 are usually not occupied by OS components, but may be used by other applications, so you better check a port list) or stop the web server to be able to use port 80.
Regards,
mav
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dear mav,
thanx for replying so fast.
i can't disable the web server yaar. i have to use the 80 port while enable the web server.
if i will select other port than 80 then what about the security of that port. suppose i select the port 10800 then if firewall has disabled this port then user has to enable it.
because of this there can be chance of hacking too. because anybody can get in with the help of that port which is enabled.
please tell me what should i say to my seniors regarding this problem.
they dont want to open the special port for the application.
ok, tell me one thing if u can that how much chance of hacking is there, if any port is opened by any company. because on 80 port there is no chance of hacking.
please give me some solution for this.
thanx again for replying.
Gagan Deep Singla
Chandigarh - INDIA
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Gagan Deep Singla wrote:
ok, tell me one thing if u can that how much chance of hacking is there, if any port is opened by any company. because on 80 port there is no chance of hacking.
Why can’t port 80 be hacked like any other port? Most web servers have been written with security in mind. When you create your server you’re going to need to put the same thought in to security as everyone else. There are no shortcuts here.
So use another port, if your customers really want this app they will open that port for your application. Just do your home work about what’s needed to keep your data safe.
-------------------------------
DEBUGGING : Removing the needles from the haystack.
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