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I have a table with only one field of type string.
This table is loaded into a list control and the user is allowed to manipulate its data by adding/removing elements on it.
When the user is ready he has the option to save this list back to the database.
Effectively I have two lists, list A which exists on the database and list B which exists in memory.
List B is mofified by the user and must be saved back to List A in the database.
In your opinions, what is the best method to use when saving list B?
1. Delete all records from A and dump B into A
2. Iterate B, checking for each item's existence in A. If item does not exist, add to A. Iterate A and check for each item's existence in B. If item does not exist in B, delete it from A
3. Like (2) but other way around. Iterate A checking for each items existence in B. If item does not exist, delete it from A. Iterate B and check for each item's existence in A if item does not exist, add it to A
There could be around 10,000 records in the list.
List A and list B do not necessarily have to exist on the same computer - they might be connected over the LAN.
Jeremy Pullicino
C++ Developer
Homepage
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my company run their project mgmt stuff on an access db. i've made various changes to this app however its extremely slow, especially on our network when more than one person wants to use it. i've since moved this to asp which everyone is happy with, despite the loss of some features. I've taken the initiative and am moving it to MySQL (boss won't cough up for ms sql) as the database is growing, new features, reporting, etc needs to be added. i've also considered moving the web app to .net, however i don't see any real benefit to the end user (just more work for myself) and its not solving the underlying issues. And one of the main bug-bears is the printing of reports -> the reports just don't cut it when printing from a web page especially if it is a multi-page report. I've come to the conclusing that i should be rewritting this app as a win32 application using C#. my biggest question is should i use a client/server configuration or just have the client application connect to the database and do whatever. the database is on a winxp machine which also serves as our file server and web server (intranet). We have approx 10 users on our network. is there a real need to go the client/server route or will the simple client app do the trick. the database is on a separate machine within our local network however the client machines can still see it and connect to it. and help, advice and/ideas are greatly appreciated.
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How do you create the reports?
modified on Monday, August 30, 2010 6:38 AM
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well, now we are still using the access db for printing multi-page reports (simply because we get the headers, footers, page number, etc automatically and nicely formatted). for single page reports we use an activex component that can print web pages without all the crap that normal prints with it (url, etc) but have to rely on html formatting.
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thanks i'll have a look at that.
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I want to return a larg set of records from database server
to the client tier -win forms-
so the question
1-what is the effective way to do this?
2- is it differ if they connected via Wan or via the Internet
thanks in advace
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Two very basic advices:
1. return ONLY the data that you really need (do not use SELECT * ...),
2. return all data using ONE batch to minimize the network traffic; don't do something like:
do
[your query]
while (...)
modified on Monday, August 30, 2010 6:42 AM
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thanks chopeen for your reply
of course i will return the data that i realy need
so the question at the case that i really need many records
when you work with disconected data you may have situation like this
you want to create dataset which have many records or if you implement your business objects
so the question again ho to do this effectively
thanks again
i need your advices gurus
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You can use a DataSet object. It works perfect on disconected enviroments. Also look information on the DataAdapter object.
The DataAdapter, will translate the modifications done to your DataSet to the DataBase.
Free your mind...
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Thanks Guillermo Rivero
it seems that i did not explain what i need exactly
i know that i can use dataset on disconected enviroments but Is it will work fine if
the returned records = 1000000 ? for example.
in situation i need this data
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Well, I once did load a DataSet with 2 million records and it worked fine.
Each record had 5 fields.
Free your mind...
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Thanks Guillermo Rivero for your help
thats ok for me but i want to ask you another question
do you know good resources (books - web sites...) about
Designing distrebuted application in .net that have real
world examples? i have some books about remoting and webservice but they are teaching technology with out real world examples .
thanks in advance
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Ok, I read somewhenre in msdn.microsoft.com[^] something about Application Blocks. And I'm almost sure that there is Distributed Application Block. There you can have guidelines on how to design Distributed Applications.
The other way is design, your own. I prefer the second one...
Free your mind...
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thanks again Guillermo Rivero i really appreciate your interact with my quetsion i will post two qestion about
paging May you take a look about them?
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To: Mohamad Al Husseiny
Hi there. Have you got a solution to your problem already?
Because im encountering that same problem. if you already have the solution please it would help me a lot thanks.
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Guys, perhaps you can help me speed up the process here.
1. sp_msx_enlist
2. sp_msx_defect
Do you run this stored proc on master server or on target server? Or both?
Thanks
norm
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HELLO! I've been developing a C# .NET application with mySQL database using ODBC driver (myodbc 3.51) to connect to the database. I've been trying to implement database transaction but encountered an error which I've no idea on how to go about in solving it.
Here's the exception that I got:
**********************************************************
Microsoft.Data.Odbc.OdbcException: ERROR [HYC00] [MySQL][ODBC 3.51 Driver]Transactions are not enabled
at Microsoft.Data.Odbc.OdbcConnection.HandleError(IntPtr hHandle, SQL_HANDLE hType, RETCODE retcode)
at Microsoft.Data.Odbc.OdbcTransaction.set_AutoCommit(Boolean value)
at Microsoft.Data.Odbc.OdbcTransaction.BeginTransaction()
at Microsoft.Data.Odbc.OdbcConnection.BeginTransactionObject(IsolationLevel isolevel)
at Microsoft.Data.Odbc.OdbcConnection.BeginTransaction(IsolationLevel isolevel)
at Solution1.Model.DBAccess.pubic() in c:\documents and settings\nat\desktop\equibs 2004\source\solution1\model\dbaccess.cs:line 478
The thread '<no name="">' (0x1f00) has exited with code 0 (0x0).
The program '[7908] Solution1.exe' has exited with code 0 (0x0).
**********************************************************
Here's what I did:
**********************************************************
OdbcConnection myConnect = new OdbcConnection(myConnString);
myConnect.Open();
OdbcCommand myCommand = myConnect.CreateCommand();
OdbcTransaction myTrans;
try
{
myTrans = myConnect.BeginTransaction(System.Data.IsolationLevel.ReadCommitted);
myCommand.Transaction = myTrans;
try
{
myCommand.CommandText = "INSERT INTO `alvin` ( `id` , `value` ) " + "VALUES ('0', '12');";
myCommand.ExecuteNonQuery();
myCommand.CommandText = "INSERT INTO `alvin` ( `id` , `value` ) " + "VALUES ('0', '24');";
myCommand.ExecuteNonQuery();
myTrans.Commit();
Console.WriteLine("Both records are written to database.");
myConnect.Close();
}
catch(Exception e)
{
try
{
myTrans.Rollback();
}
catch (OdbcException ex)
{
if (myTrans.Connection != null)
{
Console.WriteLine("An exception of type " + ex.GetType() + " was encountered while attempting to roll back the transaction.");
}
}
Console.WriteLine("An exception of type " + e.GetType() + "was encountered while inserting the data.");
Console.WriteLine("Neither record was written to database.");
}
finally
{
myConnect.Close();
}
}
catch(Exception e)
{
Console.WriteLine(e.ToString());
}
**********************************************************
Please HELP!!! Thanksss
Love my shoes
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When I last looked, a couple of years back, MySQL did not support transactions (although there were plans in the pipe-line to support them).
You should look at your version of MySQL to find out if it supports transactions - if it does then you may have to change some configuration settings.
Hope this helps.
Andy
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Thanks a bunch! Yeah, reckon that's the problem too! Thanks again!
Love my shoes
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Hi all,
I have an admin sproc that I've used for a long time; but apparently I never noticed that sp_depends doesn't return a failure value. I suppose over time I have just never checked a sproc that had no dependencies which is how I discovered this.
sp_depends raises an error if there are no dependencies unfortunately the return Value is 0 for all cases. Therefore using checking the return value is of no use. Since I use a return Value and a retCode in my sproc I was wondering if there is some system variable I can use to get the last error raised when exec a sproc from a sproc??
Currently I am checking for the table count and if it is 0 then I display the same message sp_depends would. I would rather the error number be returned in my return code so I can look up the mesage or have a custom message of my own.
Thanks
Pamela Reinskou
VersusLaw Inc.
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The @@ERROR variable holds the last error number.
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Yes, this is true; but in this case it is overwritten as soon as the next statement in the sp_depends sproc is executed. Therefore by the time my sproc receives the output the @@Error is 0 again.
I was thinking maybe there was some undocumented system function(s) that handles scope much like the identity functions, Scope_Identity and @@Ident_current.
You can check this for yourself by comparing the results of sp_depends on an object that has dependencies and one that doesn't, set a local var to return the returnValue and also try to grab the @@Error and you will see in all cases the returnValue is 0 and @@Error is 0. For now I am trapping it and using table count that seems to be the only way to figure it out.
Thanks.
Pamela Reinskou
VersusLaw Inc.
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When I try to access "MS Access" .mdb database using "native" Microsoft.Jet.OLEDB.4.0 provider I'm experiencing a problem with deleting of multiple records from previously retrieved recordset.
Here is an example:
// first, I open database in very usual way using ATL-based classes (mostly generated by OLEDB consumer-template wizard in VS)
CDataSource db;
CDBPropSet dbinit(DBPROPSET_DBINIT);
...................................
dbinit.AddProperty(DBPROP_AUTH_PASSWORD, OLESTR(""));
dbinit.AddProperty(DBPROP_AUTH_USERID, OLESTR("Admin"));
dbinit.AddProperty(DBPROP_INIT_DATASOURCE, (LPOLESTR)szDBName);
dbinit.AddProperty(DBPROP_INIT_MODE, (long)16);
hr = db.Open(_T("Microsoft.Jet.OLEDB.4.0"), &dbinit);
if( SUCCEEDED(hr) )
{
hr = m_session.Open( db );
return hr;
}
// then I use generated accessor class
(something like class CProducts : public CCommand<caccessor<cproductsaccessor> >)
to open a rowset as a result of some SQL statement:
CProducts rs;
rs.Open();
// When I iterate through received recordset, processing data and deleting records using some criteria (or just all of them) like:
while( S_OK == rs.MoveNext() )
{
..................... // do something here
rs.Delete();
}
I receive "DB_S_ENDOFROWSET" just right after the second deletion, even though there is a lot more records in the recordset - without such deletion inside a loop I can successfully traverse entire recordset (all records) with no problems at all.
When I open DataSource using "MDASQL" as a provider instead of "Microsoft.Jet.OLEDB.4.0" everything works just fine (as it is supposed to work).
Initially blamed msjetoledb40.dll module, but installing the latest MSJETOLEDB40 Service Pack SP8 did not solve the problem.
Did I do something wrong, or somebody else had such problem and knew good workaround?
Best regards,
Andrey
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I haven't seen this problem, but that's probably because I'm fairly new to this. Generally I've had good luck with a slightly different structure, though. Try
while (!rs.EOF)
{
.............//do stuff
rs.Delete();
rs.MoveNext();
}
and see what happens. According to MSDN,
"After a successful deletion, the recordset's field data members are set to a Null value, and you must explicitly call one of the Move functions in order to move off the deleted record. "
I know that your existing while loop is supposed to do this, but it may be that the Jet Database Engine is looking for something more explicit.
"Another day done - All targets met; all systems fully operational; all customers satisfied; all staff keen and well motivated; all pigs fed and ready to fly" - Jennie A.
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