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Hi,
I have a query with regards to data sets.
I have the following declarations in C#.NET, it's just brief, so I hope it makes sense:
SqlDataAdapter adptContacts;
dsContacts.ContactsRow rowNew;
rowNew = dsContacts.Contacts.NewContactsRow();
rowNew.ContactID = GetNewContactID();
rowNew.FirstName = txtFirstName.Text;
rowNew.LastName = txtLastName.Text;
I have code that adds data to the new row, then I add the code to the data set using the following code:
dsContacts.Contacts.AddContactsRow(rowNew);
I modify the database like this:
adptContacts.Update(dsContacts);
I just want to know when adding data to the database like I did. As far as I understand it, a dataset contains data retrieved from the database. So when I do my update, does it delete the data in the table and all the data in the data set, or does it just add the new row to the table?
Brendan
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DataRows have a DataRowState property which defines if a datarow is modified, added or deleted. Check ur rowNew.RowState and you will se its System.Data.DataRowState.Added.
When u update the source datatable in ur underlying database, the dataadapter
method adptContacts.Update(dsContacts) will use the adapter's DeleteCommand for the Contact's table to delete any Deleted datarows, the InsertCommand for any Added datarows and the UpdateCommand for any modified rows ur datatable might have.
In ur case, ur DataTable only has one Added row, so the dataadapter will add ur row to the underlying database datatable. It wont delete anything anywhere.
In ur code, I seem to be missing where un initialize the adptContacts DataAdaper. U have to create and assign the SqlCommands to it. An easy way is to create the DataAdapter in the designer, it will create all commands by itself, unless ur querying more than one DataTable through a JOIN.
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Look at the IDataAdapter.Update [^]IDataAdapter.Update documentation in MSDN. It is clearly explained.
--------
"I say no to drugs, but they don't listen."
- Marilyn Manson
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Hi,
I am using collection to bind data to datagrid.
Dim oCars as CarCollections = New CarCollections
DataGrid1.DataSource = oCars
Everyithing work fine but there is a sorting problem.
If I do so, there is no sorting features in DataGrid. When I bind DataSet to Datagrid I can Sort data in DataGrid by clicking on columns header. DataGRid automaticly sort filled data according clicked colum.
When I bind datagrid to Collection that features is missing.
What should i do, in Collection class - CarsCollection, to have sorting features back
Thanks in advance
P.S. Sorry for bad English
... Never argue with an idiot, they will drag you down to their level and beat you with experience
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Tancev Sasa wrote:
Everyithing work fine but there is a sorting problem.
IIRC, your class needs to implement IComparable for sorting work.
Yes, even I am blogging now!
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Can you send me a link where I can find an example or something that will help me
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IComparable Interface[^]
Simply put, you just need to implement a single method, CompareTo(obj), that will compare this instance to another object, for order purposes. It must return -1 if it's smaller (or lower rank), 0 if it's equal (or the same rank), and +1 if it's bigger.
Yes, even I am blogging now!
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Hi,
I want to detetmin parent class
For instance there is a Cars collection with Car item.
Cars collection has some property that I need to access from Car item.
Cars collection
Property_01
Property_02
CarItem(s) (Type, Name, Year, ...)
I want to obtain the value of Property_02.
Every CarItem is already inside Cars collection and I am sure that there is way to obtain parent class.
How to do that?
Do not send answers like "You have to hold a reference to the CarsCollection in the CarItem:"
public class CarsCollection : List
{
public CarItem CreateCarItem()
{
return new CarItem(this);
}
}
I think that is something about iComponent or something similar.
Tancev Sasa
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Tancev Sasa wrote:
Do not send answers like "You have to hold a reference to the CarsCollection in the CarItem:"
Ok, we won't but there are only two ways of doing it:
1. The answer you don't want
2. Searching all the collections in your program for that specific instance.
Tancev Sasa wrote:
I think that is something about iComponent or something similar.
A Component holds a reference to its container in the Container property.
Yes, even I am blogging now!
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I want to make a PropertyGrid control readonly on runtime.
I try to use ReadOnlyAttribute for a class or property but I don't know if I can change the value of the attribute on runtime.
Any other ideas how to make the control readonly ?
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Hey people, first post for me!
I am creating a network monitoring tool that will monitor the amount of traffic going out and coming into a computer on a 10baseT connection. Was wondering if there is either any code out there that can count the number of data packets going out and coming into an ethernet connection. I've looked what feels like everywhere but still can't find anything : ( ( If anyone here has either some suggestions of stuff that already exists, or is savvy enough to put some code together quickly, could you point me in the right direction please?
I'm also going to be using .NET as part of this program, so if that's needed to do what I need then that's fine.
Cheers
Jeff
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Cheers, I'll have a look at that and let you know if it's got what I need....or if I need some help looking through it to find what I need 
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also try using System.Diagnostics.PerformanceCounter; You can drag one of the desired category (IP/datagrams sent/recieved) from your server explorer.
there are no facts, only interpretations
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So I've had a quick look at what you suggested do I create a windows application and then a form and then just drag and drop the thing I need onto the form and Visual Studio does all the working out for me? If that's the case....then excellent
Cheers for the help so far people. Been nice to find a forum that responds to shouts for help
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yes, letting Visual Studio do most of the work for you is possible and quite easy. If you're not sure exactly what data you need, try playing first with windows "perfmon" program, which basically gives the same parameters, though with quite poor graphics for my taste.
there are no facts, only interpretations
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good day!! is there a way to retrieve values from documentproperties in winspool.drv?? sample values are the number of pages, and orientation.. many thanks!!!
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Hi,
Given a Bitmap that is embedded into a windows metafile (WMF) thereby allowing it to be added to a rich text box.
I have been trying to recreate the bitmap from the WMF.
So assuming I have a windows metafile that is represented in the RichText box as
the control string :
"{\pict\wmetafile8\picw[N]\pich[N]\picwgoal[N]\pichgoal[N] [BYTES]}"
where BYTES are the HEX representation of an image.
How would I convert this back into a bitmap?
My thought was to use the MetaFile class constructing it from a stream derived somehow from the BYTES above, and then as the Metafile class is an Image it can be transformed into a Bitmap which is also an Image.
Any help would be very useful as I keep hitting a brick wall, but as a convert from C++, my C# isnt that good yet.
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The "ExecuteNonQuery" I'm trying to execute a 10000 INSERT statement (which
executes fine in SQL+). The INSERT statement executes properly 30% of the
time( I use progress bar to see), but throws this error sometimes. please help me! I don't know what's happening.
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What is the error?
Charlie
if(!curlies){ return; }
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I think the problem cause .ldb file that create by microsoft access and it don't delete. what can i do?
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You can safely delete an .ldb file that didn't get deleted automatically. .ldb files contain computer and user information, as well as row locking information. The information it contains is about your database, but deleting the file will not change anything in your database.
All that said, however, I don't think that would cause INSERTs to fail. When I asked what the error was, I was referring to the message you get when the INSERT fails. Simply saying that you can't do something is only one part. You need to give some clues to get meaningful help.
Charlie
if(!curlies){ return; }
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Hi, there's one problem with SortedList - that's it doesn't permit duplicate keys - so, it's more like a "sorted Set" - What collection class should I use for this purpose?
Thanks!
Norman Fung
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Just found a solution:
class Employee : IComparable
protected int _UIN
protected double _salary
...
...
public int CompareTo(object o) {
if(o is Employee) {
Employee other = (Employee) o
} else {**throw exception**}
...
switch(sortOption) {
...
case SortOption.SORT_SALARY:
ret=this.Salary.CompareTo(_other.Salary)
if(ret==0) {
ret=this.UIN.CompareTo(other.UIN)
}
break;
case else:
...
}
...
return ret;
}
Since UIN is bound to be unique, there'll never be a chance for duplicate keys exception on SortedList inserts.
Norman Fung
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