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If you copy pasted these dropdowns, most likely the datasource and the binding properties have been copied too.
Check the data sources and three properties you have bound to.
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Actually I am setting values of all the dropdowns in the same functions, so I had to copy/paste the code. Here is the code
<pre lang="c#">
private void LoadStudents()
{
StringBuilder sb = new StringBuilder();
DataTable dt = GetStudentsList(); //get data from database
DataTable dt2 = MakeTable(); //to insert concatenated NAMEs with IDs
for (int i = 0; i < dt.Rows.Count; i++)
{
// concatinate id with name
sb.Append(dt.Rows[i][0].ToString().Trim());
sb.Append(" --- ");
sb.Append(dt.Rows[i][1].ToString().Trim());
string studentName = sb.ToString();
dt2.Rows.Add(studentName );
sb.Clear();
}
LoadAccountsIntoCombos(dt2);
}
private void LoadAccountsIntoCombos(DataTable dt2)
{
//Show Students
combo1.DataSource = dt2;
combo1.DisplayMember = "StudentName";
combo1.SelectedIndex = 0;
combo2.DataSource = dt2;
combo2.DisplayMember = "StudentName";
combo2.SelectedIndex = 0;
combo3.DataSource = dt2;
combo3.DisplayMember = "StudentName";
combo3.SelectedIndex = 0;
}
</pre>
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I think (it has been a while since I used a datatable) you can use something like
combo2.DataSource = dt2.Copy();
Basically you need to make a copy of the datatable so you are not continiously interacting with the same data.
Never underestimate the power of human stupidity
RAH
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Mycroft Holmes wrote: combo2.DataSource = dt2.Copy();
That sounds perfect.
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Thnx..it helped...hence voted 
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In short, you assigned the same 'reference' to the comboboxes. You need to have a 'deep copy' assigned to them. (I also used to make that same mistake )
V.
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Bear in mind that this copies the entire data table, which is often vast overkill for a combo box. In this case the table appears to be just ID/value so this is probably a correct solution, but the questioner shouldn't take away that this is something that should be applied to all data binding scenarios.
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Generally (I love generalisations) a combo table tends to be small. However one must expect some common sense to be applied to any solution. The OP was chasing the problem of using the same datasource, the size of the datasource was not part of the problem 
Never underestimate the power of human stupidity
RAH
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Indeed, the copying is fine for this problem. I just wanted to raise the issue so the next time this guy wants to do something similar he might be reminded to think about it.
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You should not duplicate the data, instead you should use an explicit BindingSource (DataContainer -> BindingSource -> Control), that way each binding would be distinct, and would hold its own state.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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This is the best solution and follows DRY principle.  to Luc Pattyn
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how to get names and count of tables in a database from sqlserver and MSAccess?
could u tell me pls?
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While some database systems provide that functionality in various ways, with any database system that provides an ADO.net provider, the Connection derives (or should derive*) from System.Data.Common.DbConnection, which has a GetSchema method which returns a DataTable with that information. So I have been using the following:
System.Data.Common.DbConnection con =
this.command.Connection as System.Data.Common.DbConnection ;
if ( con != null )
{
System.Data.DataTable temp = con.GetSchema
(
"TABLES"
) ;
temp.DefaultView.RowFilter = "TABLE_TYPE='TABLE' OR TABLE_TYPE='BASE TABLE'" ;
temp.DefaultView.Sort = "TABLE_NAME" ;
This is good enough for SQL Server, Access, and Excel. But this is old code; a week or so ago I started using Oracle and MySql (and FireBird, just because) again and found that the tables provided by them are more different than I expected so I had to adapt.
* I'm looking at you Cache. 
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PIEBALDconsult wrote: a week or so ago I started using Oracle and MySql
Poor bastard, you have my sincere sympathies.
Never underestimate the power of human stupidity
RAH
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Yes, thank you. Fortunately all I need to do is pull some data from them and make copies in SQL Server, but I still need to be sure that my data access library works with them.
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Lets say I have an object o, o.Ref = o1. o1 references o2 and o2 references o3.
If I set o.Ref = null, is the GC going to dispose of o1, o2 and o3? Seems like there will be no reference to o1, so that'll be disposed resulting in no ref to o2 and so on??
What I'm getting at, if I have a binary tree structure and set the root to null, are all the nodes going to get disposed in cascade fashion?
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SledgeHammer01 wrote: What I'm getting at, if I have a binary tree structure and set the root to null, are all the nodes going to get disposed in cascade fashion?
The garbage collector will move them as soon as your application can no longer reach the object from code. It's not guaranteed in which order they are moved.
Bastard Programmer from Hell 
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SledgeHammer01 wrote: are all the nodes going to get disposed in cascade fashion?
No, and disposing has nothing to do with it, and there is absolutely no reference counting. What will happen is this:
The next time the garbage collection does a collection on the generation that these things are in (which may not be ever), it will find all of them to be unreachable, and they will not be promoted to the next generation (or an older part of the same generation, if it's generation 2) and not copied to the target memory segment.
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There are two parts to that question:
1.
if o.Ref held the only remaining reference to o1 (and o1 the only reference to o2, etc), then setting it null will make o1 (and o2 and o3) eligible for garbage collection. It will not call Dispose(), and it will not force a garbage collection to occur. When you later need more memory than is currently free inside your process, the GC may or may not free those objects (depends on their generation); if they have finalizers, then those would be called. However, if your app came to a halt, no memory would be freed, no Dispose would be called.
2.
When the GC determines all of o1, o2, and o3 are no longer alive, they will all be scrapped, in no particular order. One pointing to the other does not influence that.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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Ah, thanks.
I thought it might look through and see that o1 doesn't have any references to it, so it would make that eligible. But it would see that o2 has a ref from o1 which hadn't been collected yet, etc.
Seems like the GC is smarter then that .
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We have a need to send very large files to an internal FTP server. These files are videos that may last as long as an hour. All of the FTP sample I find have the standard code in them:
request.Method = WebRequestMethods.Ftp.UploadFile;
request.Timeout = CONNECTION_TIMEOUT;
request.ReadWriteTimeout = CONNECTION_TIMEOUT;
request.UsePassive = false;
if (credentials != null)
request.Credentials = credentials;
StreamReader sourceStream = new StreamReader(source);
byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
sourceStream.Close();
request.ContentLength = fileContents.Length;
Stream requestStream = request.GetRequestStream();
requestStream.Write(fileContents, 0, fileContents.Length);
requestStream.Close();
This logic gives us an out-of-memory condition with very large files. What I'd like to do is have it send the file as a multi-part file sent as small chunks instead of a single large stream.
Does anyone know how this is implemented?
Software Zen: delete this;
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I see no reason to go for complex schemes, however it makes no sense to me that you first read the entire file into memory, and then send it in a single write. Both operations are stream operations, so use them as such, with small amounts, and in a loop.
And then, I'm puzzled by the Encoding.UTF8.GetBytes statement; there is no text involved anywhere, so why would one need an Encoding? All it takes is byte transfers: byte array in, byte array out.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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Well, Luc, you took my post too literally.
The code I posted was one of the first examples I quickly grabbed.
Essentially all the code is as follows:
get a stream reader, read the data into a byte array, create a stream writer, feed it the byte array.
Our issue as I noted in the example is that the byte[] buffer = stream.ReadToEnd() always throws an out of memory exception.
I was ready that for very large files you can do a multi-part so that you read and transmit small packets and the FTP server puts the packets together into the original massive file. That is what I'm looking for so that we do not blow out our memory again.
Software Zen: delete this;
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you should read my post and take it literally.
Do NOT use ReadToEnd(); use a loop, and read and write smaller chunks.
That is called streaming.
Luc Pattyn [My Articles] Nil Volentibus Arduum
Fed up by FireFox memory leaks I switched to Opera and now CP doesn't perform its paste magic, so links will not be offered. Sorry.
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