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Hi,
I am an intermediate programmer i have working knowledge on databases in various programming programming languages. What my problem is I dont know the basics of database connections till now I have just used copy-paste procedure while connecting databases so I want to know the basics of integrating database in my applications. I need the information right from the begining like
1. What is DataSource?
2. What is Data Provider?
etc. important terms that are required initially when we start an application to integrate database
thanks,
Sudhir.
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You would start by reading the documentation, http://msdn.microsoft.com/en-us/library/a6cd7c08(v=VS.71).aspx[^]
Why is common sense not common?
Never argue with an idiot. They will drag you down to their level where they are an expert.
Sometimes it takes a lot of work to be lazy
Please stand in front of my pistol, smile and wait for the flash - JSOP 2012
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I need to add
using System.Web.Script.Serialization; but when I try to do add reference , it disbaled in .net component. I am using VS 2008.
I read on internet that it is available in 3.5 but in my visual studio some components of 3.5 are enable but some are disables.
I also search my system for System.Web.Extensions.dll and it is present in v3.5 folder.
Please suggest hwo to add?
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You should change the .Net Framework version to .Net Framework 3.5 full, rather than .Net Framework 3.5 Client Profile and then all .Net 3.5 libraries should be available. You can do this in your application properties under the Application tab - Target framework.
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
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Glad to help
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
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Now email MS and ask them to get rid of the stupid client profiles.
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Sure thing.
....emailing MS
Sorry no reply. 
When I was a coder, we worked on algorithms. Today, we memorize APIs for countless libraries — those libraries have the algorithms - Eric Allman
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Hi all, I don't know whether this question should be posted here or in a the database forum because it involves both C# and database query statements, but here goes. I am trying to determine if a username password pair exists in the Engineer Table or in the writer table. First I check the Engineer Table for the username password pair using the SQL Count Function. If the pair does not exist then the Count Function returns 0, if it does exist then the Function returns a number greater than 0. I'm using Stored Proc1 to search in the Engineer Table and Stored Pro2 to search in the Writer Table. Below are my stored procedures.
Proc1
SELECT Count(*)
FROM Engineer
WHERE [User Name]= [@UserName] AND [Password] = [@Password] ;
Proc2
SELECT Count(*)
FROM Writer
WHERE [User Name]= [@UserName] AND [Password] = [@Password] ;
The following is my code
public int StaffExists(string myPath, string UserName, string Password)
{
OleDbConnection OleConn = null;
OleDbCommand oCommand = null;
OleDbParameter param = null;
OleConn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + myPath + "");
OleConn.Open();
oCommand = new OleDbCommand("Proc1", OleConn);
oCommand.CommandType = CommandType.StoredProcedure;
param = new OleDbParameter("@UserName", UserName);
oCommand.Parameters.Add(param);
param = new OleDbParameter("@Password", Password);
oCommand.Parameters.Add(param);
oCommand.CommandText = "Proc1";
int Count = (int)oCommand.ExecuteScalar();
OleConn.Close();
oCommand.Dispose();
int UserCount = Count;
int UserCount2 = 0;
if (UserCount > 0)
{
return UserCount;
}
else
{
if (UserCount == 0)
{
OleConn.Open();
oCommand = new OleDbCommand("Proc2", OleConn);
oCommand.CommandType = CommandType.StoredProcedure;
param = new OleDbParameter("@UserName", UserName);
oCommand.Parameters.Add(param);
param = new OleDbParameter("@Password", Password);
oCommand.Parameters.Add(param);
oCommand.CommandText = "Proc2";
UserCount = (int)oCommand.ExecuteScalar();
OleConn.Close();
oCommand.Dispose();
UserCount2 = UserCount;
if (UserCount2 > 0)
{
}
else
{
}
}
return UserCount2;
}
}
The problem is no matter what username or password is entered they come back as invalid. Please help, thanks in advance.
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The [] brackets around the parameters look strange. What about
WHERE [User Name]= @UserName AND [Password] = @Password
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SqlCommand.ExecuteScalar Method
Executes the query, and returns the first column of the first row in the result set returned by the query. Additional columns or rows are ignored.
Your c sharp code is correct.
I think you should check the white space in your parameters (@UserName and @Password) or check the white space in your engineer and writer table for column Username and Password.
Rohit Kumar
Senior Software Engineer
Smart Sign India Pvt Ltd
Jaipur
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I'm fairly new to programming in general and C# in particular. Following code throws an "Object reference not set to an instance of an object" exception.
public class quote
{ ...
public string[] data;
public string[] date;
public string[] release;
public string[] baseID;
...
DataTable t2 = new DataTable();
...
for (int i = 0; i < t2.rows.count + 1; i++)
{
DataRow r2 = t2.Rows[i];
this.baseID[i] = (string)r2["BASE_ID"];
this.data[i] = (string)r2["Data"];
this.date[i] = Convert.ToString(r2["Date"]);
this.release[i] = (string)r2["Release"];
}
I think I understand why it doesn't work....but I'm not sure what I should be doing instead. Any help is greatly appreciated.
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The issue is that your declarations public string[] data;, etc. do not create/allocate an array, they only specify that data will be an array.
You still need to create the arrays with new, just like you do with DataTable.
So it looks like, right after your t2.Rows is "full":
int rowCount = t2.Rows.Count;
this.baseID = new string[rowCount];
this.data = new string[rowCount];
this.date = new string[rowCount];
this.release = new string[rowCount];
etc.
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Jacob Rotary wrote: I'm not sure what I should be doing instead
Instead of what you are doing now? Or, doing something to fix your existing problem?
Why is common sense not common?
Never argue with an idiot. They will drag you down to their level where they are an expert.
Sometimes it takes a lot of work to be lazy
Please stand in front of my pistol, smile and wait for the flash - JSOP 2012
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Wes Aday wrote: Instead of what you are doing now?
<cruel>Them burgers ain't gonna flip themselves.</cruel> 
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Good one.... and oh so cruel. I do not think that we will have a shortage of flippers any time soon anyway 
Why is common sense not common?
Never argue with an idiot. They will drag you down to their level where they are an expert.
Sometimes it takes a lot of work to be lazy
Please stand in front of my pistol, smile and wait for the flash - JSOP 2012
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Jacob Rotary wrote: i < t2.rows.count + 1
That just don't look right. 
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Quote: for (int i = 0; i < t2.rows.count + 1; i++)
You should note that indexing in a table starts at 0 in .NET libraries, and not 1. Meaning List.Count - 1 would be the last element.
There are some programs that starts at 12 though Matlab, Excel and Word have this property in idexing, to great frustration if you dont know it
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Apart from the issue of the missing object creation, I suggest to use Lists instead of Arrays: an array has a fixed size, and that size must be known when you create it. E.g.
public List<string> data = new List<string>();
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If I were writing this code, I'd write something like this:
public class QuoteItem
{
public string Data;
public string Date;
public string Release;
public string BaseId;
}
public class Quote
{
public List<QuoteData> Quotes = new List<QuoteData>();
...
foreeach (DataRow row in ts.Rows)
{
QuoteData quote = new QuoteData();
quote.BaseId = (string)r2["BASE_ID"];
quote.Data = (string)r2["Data"];
quote.Date = Convert.ToString(rs["Date"]);
quote.Release = (string)r2["Release"];
Quotes.Add(quote);
}
}
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"Object reference not set to an instance of an object" is almost never hard to debug. The debugger stops on the line that has trouble, just look for the thing that is null.
If no nulls are visible, usually that's the result of doing something like someMethod().something, ie dereferencing the result of a method (which is not something the debugger shows you, unfortunately). Refactor the code so that the result is stored in its own variable. That's usually a good thing to do anyway.
You've already been told what's null (and you've been made aware of other problems), but this is how you can fix it in many cases in the future, without having to ask for help.
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Hello everyone,
I have a project that requires me to gather inventory data for my computer. I am having problems trying to get the properties of the monitors attached to my computer.
I have one computer that can potentially use a max of 4 monitors, wherein I have a primary monitor and 3 other potential monitors which act as extension screens when I move my mouse to them ( depending on whether they are connected or not ).
I need to grab the following information from each monitor :
DeviceId,
Name,
Horizontal and Vertical resolution,
Whether or not the monitor is the primary one ( a true or false value will suffice ).
I tried using the WMI, Win32_DesktopMonitor class but it is only giving me ONE monitor's results ( the primary monitor ).
I then tried using the Win32_PnPEntity class.
This works, and gives me the number of monitors attached to my computer, but it only gives me Name and DeviceId ( no horizontal and vertical resolution information in this class ).
I forgot to add and I apologize for this... this application I am building will eventually be ran as a Windows Service application.
I discovered this during my development ---- when I tried the Screen class (using the System.Windows.Forms.Screen), the result is erratic.
If I ran the program as a pure console application, it works and gives me the right number of monitors attached to my computer, when I ran the same program as a windows service, it does not. It only gives me ONE ( the primary monitor ).
Does anyone know of a Class provided by .NET 4 that will help me gather the information I need?
I am using .NET Framework 4 and building my application as a Windows Service Application.
For everyone's information, I am using the following environment:
1) .NET 4
2) Visual Studio 2010
3) C# programming language
4) Windows service Application
Any suggestions and advise will be highly appreciated.
modified 30-Aug-12 8:21am.
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There is no class that will do this. Gathering the information you want is problematic at best.
I had to do the same thing, but not use .NET to do it. I ended up writing a class in VBScript that parsed the EDID data in the registry to get all of this information. The problem with that is the EDID data for every monitor to ever be attached to the machine is in there, and there is no way to find out which monitors are actually attached and which is the primary.
The data is under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY
What everything in that pile of data means can be found here[^].
My class supported data formats for all EDID versions up to and including 1.3.
No, I can't give it to you.
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Monthly payment of $10000, the recruitment of Trojan horse to prepare the programmer
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Hi,
I got the following error on server
Method not found: 'Void IBM.Data.DB2.DB2Connection.set_ParameterStreaming(Boolean)
It worked fine on my desktop with Visual Studio 2010.
I'm appreciate if someone can help.
Thanks,
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