I was going through some old code that was written in years past by another developer at my organization. Whilst trying to improve this code, I discovered that the query it uses had a very bad problem.
OdbcDataAdapter financialAidDocsQuery =
new OdbcDataAdapter(
#"SELECT a.RRRAREQ_TREQ_CODE,
b.RTVTREQ_SHORT_DESC,
a.RRRAREQ_TRST_DESC,
RRRAREQ_STAT_DATE,
RRRAREQ_EST_DATE,
a.RRRAREQ_SAT_IND,
a.RRRAREQ_SBGI_CODE,
b.RTVTREQ_PERK_MPN_FLAG,
b.RTVTREQ_PCKG_IND,
a.RRRAREQ_MEMO_IND,
a.RRRAREQ_TRK_LTR_IND,
a.RRRAREQ_DISB_IND,
a.RRRAREQ_FUND_CODE,
a.RRRAREQ_SYS_IND
FROM FAISMGR.RRRAREQ a, FAISMGR.RTVTREQ b
WHERE a.RRRAREQ_TREQ_CODE = b.RTVTREQ_CODE
and a.RRRAREQ_PIDM = :PIDM
AND a.RRRAREQ_AIDY_CODE = :AidYear ",
this.bannerOracle);
financialAidDocsQuery.SelectCommand.Parameters.Add(":PIDM", OdbcType.Int, 32).Value = this.pidm;
financialAidDocsQuery.SelectCommand.Parameters.Add(":AidYear", OdbcType.Int, 32).Value = this.aidYear;
DataTable financialAidDocsResults = new DataTable();
financialAidDocsQuery.Fill(financialAidDocsResults);
FADocsGridView.DataSource = financialAidDocsResults;
FADocsGridView.DataBind();
The problem is that the column a.RRRAREQ_TRST_DESC does not exist. A fact you learn very quickly when running it in Oracle SQL Developer.
The strange thing?
This code works.
The gridview binds successfully. (It doesn't try to bind to that field.) And it's been in production for years.
So, my question is...why? I've never seen a bad query work. I've never seen Oracle allow it or a data provider hack around it.
Does anyone have any idea what's going on here?
Hmmm...A few things to check:
Does this code actually run? It may seem silly to suggest this, but there may be a newer file that replaced this one.
Is an exception being squelched by your code? (Anyone who would name columns like that is definitely capable of squelching those pesky exceptions)
Is the exception being squelched by 3rd party code? (Not as likely, but sometimes 3rd party code prefers to use annoying error codes instead of exceptions).
Past those suggestions, I'm not sure.
EDIT:
Revisiting the 2nd point, if you are working in ASP.NET, check that there is no global-level exception handler that is squelching exceptions. I ran into that problem on one site that I worked on and found dozens of exceptions in a single day.
Try running
select * from v$sql where sql_fulltext like '%a.RRRAREQ_TRST_DESC%'
shortly after you bind the grid. That will tell you if the statement was actually seen by Oracle. Note that you should only see the above query if it was not seen by Oracle.
Use ODBC trace log to see if this query is really send to database, and see what database returns. Then use any other ODBC based database tool and check if this query work from this tool. As an ultimate test you can write simple Python script. Easiest way it to use ActiveState Python 2.x with odbc module included. Test code can look like:
import odbc
connection = odbc.odbc('dnsname/user/password')
cursor = connection.cursor()
cursor.execute("select ...")
for row in cursor.fetchall():
print '\t'.join([str(r) for r in row])
If there was no error in your program and an error in other tools then compare theirs ODBC traces.
If I understand what the original author was trying to do, and with Banner that is never easy to figure out, then this query should be correct:
SELECT a.rrrareq_treq_code,
b.rtvtreq_short_desc,
c.rtvtrst_desc,
rrrareq_stat_date,
rrrareq_est_date,
a.rrrareq_sat_ind,
a.rrrareq_sbgi_code,
b.rtvtreq_perk_mpn_flag,
b.rtvtreq_pckg_ind,
a.rrrareq_memo_ind,
a.rrrareq_trk_ltr_ind,
a.rrrareq_disb_ind,
a.rrrareq_fund_code,
a.rrrareq_sys_ind
FROM faismgr.rrrareq a,
faismgr.rtvtreq b,
faismgr.rtvtrst c
WHERE a.rrrareq_treq_code = b.rtvtreq_code
AND a.rrrareq_trst_code = c.rtvtrst_code
AND a.rrrareq_pidm = :PIDM
AND a.rrrareq_aidy_code = :AidYear;
Well, let's file this in the false alarm category.
I decided to have our VAT send a copy of the DLL from test. I pulled it apart with reflector and found, much to my embarrassment, that the query is right. Which makes sense.
I still can't figure out why my working copy would have one incorrect field_name. To my knowledge, I had never touched this file before this week. But, SVN doesn't have any history showing this error in previous versions.
So strange...maybe I'm losing my mind.
Thanks for all of the quality feedback on this question. I certainly learned some new trouble shooting techniques and for that I'm very appreciative. :)
Happy coding,
Clif
Related
I am currently facing an issue where it takes quite a while to process information from a server, and I would like to provide active feedback for the user to know what is going on while the application appears to be just sitting around.
A little about the application: it allows the user to pull all databases from a specified server along with all content within those databases. This can take quite a while sometimes, since some of our databases can reach 2TB in size. Each server can contain hundreds of databases and so as a result, if I try to load a server with 100 databases, and 30% of those databases are over 100GB in size, it takes a good couple of minutes before the application is able to run effectively again.
Currently I just have a simple loading message that says: "Please wait, this could take a while...". However, in my opinion, this is not really sufficient for something that can take a few minutes.
So as a result, I am wondering if there is a way to track the progress of the SqlConnection object as it is executing the specified query? If so, what kind of details would I be able to provide and are there any readily available resources to look over and better understand the solution?
I am hopeful that there is a way to do this without having to recreate the SqlConnection object altogether.
Thank you all for your help!
EDIT
Also, as another note; I am NOT looking for handouts of code here. I am looking for resources that will help me in this situation if any are available. I have been looking into this issue for a few days already, I figure the best place to ask for help is here at this point.
Extra
A more thorough explanation: I am wondering if there is a way to provide the user with names of databases, tables, views, etc that are currently being received.
For example:
Loading Table X From Database Y On Server Z
Loading Table A From Database B On Server Z
The SqlConnection has an InfoMessage-Event to which you can assign a method.
Furthermore you have to set the FireInfoMessageEventOnUserErrors-Property to true.
No you can do something like
private void OnInfoMessage(object sender, SqlInfoMessageEventArgs e)
{
for (var index = 0; index < e.Errors.Count; index++)
{
var message = e.Errors[index];
//use the message object
}
}
Note that you should only evaluate messages with an errorcode lower then 11 (everything above is a 'real' error).
Depending on what command you are using sometime the server already generates such info messages (for example at VERIFY BACKUP).
Anyways you can also use this to report progress form a stored procedure or a query.
Pseudocode (im not an sqlguy):
RAISEERROR('START', 1,1) WITH NOWAIT; -- Will raise your OnInfoMessage-method
WHILE
-- Execute something
RAISEERROR('Done something', 1,1) WITH NOWAIT; -- Will raise your OnInfoMessage-method
-- etc.
END
Have fun with parsing, cause remember: such messages can also be generated by the server itself (so it is probably a good idea to start your own, relevant "errors" with a satic sequence which cannot occur under nomal circumstances).
I'm a bit newbie still and I have been assigned with the task of maintaining previosuly done code.
I have a web that simulates SQL Management Studio, limitating deleting options for example, so basic users don't screw our servers.
Well, we have a function that expects a query or queries, it works fine, but our server RAM gets blown up with complex queries, maybe it's not that much data, but its casting xml and all that stuff that I still don't even understand in SQL.
This is the actual function:
public DataSet ExecuteMultipleQueries(string queries)
{
var results = new DataSet();
using (var myConnection = new SqlConnection(_connectionString))
{
myConnection.Open();
var sqlCommand = myConnection.CreateCommand();
sqlCommand.Transaction = myConnection.BeginTransaction(IsolationLevel.ReadUncommitted);
sqlCommand.CommandTimeout = AppSettings.SqlTimeout;
sqlCommand.CommandText = queries.Trim();
var dataAdapter = new SqlDataAdapter { SelectCommand = sqlCommand };
dataAdapter.Fill(results);
return results;
}
}
I'm a bit lost, I've read many different answers but either I don't understand them properly or they don't solve my problems in any way.
I know I could use Linq-toSql- or Entity, I tried them but I really don't know how to use them with an "unknown" query, I could try to research more anyway so if you think they will help me approaching a solution, by any means, I will try to learn it.
So to the point:
The function seems to stop at dataAdapter.Fill(results) when debugging, at that point is where the server tries to answer the query and just consume all its RAM and blocks itself. How can I solve this? I thought maybe by making SQL return a certain amount of data, store it in a certain collection, then continue returning data, and keep going until there is no more data to return from SQL, but I really don't know how to detect if there is any data left to return from SQL.
Also I thought about reading and storing in two different threads, but I don't know how the data that is in one thread can be stored in other thread async (and even less if it solves the issue).
So, yes, I don't have anything clear at all, so any guidance or tip would be highly appreciated.
Thanks in advance and sorry for the long post.
You can use pagination to fetch only part of the data.
Your code will be like this:
dataAdapter.Fill(results, 0, pageSize);
pageSize can be at size you want (100 or 250 for example).
You can get more information in this msdn article.
In order to investigate, try the following:
Start SQL profiler (it is usually installed along with SSMS and can be started from Management Studio, Tools menu)
Make sure you fill up some filters (either NT username or at least the database you are profiling). This is to catch as specific (i.e. only your) queries as possible
Include starting events to see when your query starts (e.g. RPC:Starting).
Start your application
Start the profiler before issuing the query (fill the adapter)
Issue the query -> you should see the query start in the profiler
Stop the profiler not to catch other queries (it puts overhead on SQL Server)
Stop the application (no reason to mess with server until the analysis is done)
Take the query within SQL Management Studio. I expect a SELECT that returns a lot of data. Do not run as it is, but put a TOP to limit its results. E.g. SELECT TOP 1000 <some columns> from ....
If the TOPed select runs slowly, you are returning too much data.
This may be due to returning some large fields such as N/VARCHAR(MAX) or VARBINARY(MAX). One possible solution is to exclude these fields from the initial SELECT and lazy-load this data (as needed).
Check these steps and come back with your actual query, if needed.
Background:
Using C# in the ASP.Net code-behind to call a SQL stored procedure via LINQ-to-Entities.
Also, please note that I am a complete newbie to all of this.
Problem:
I'm calling a stored procedure to get the max_length of a column in my database.
It keeps returning "Sequence Contains No Elements" when utilizing .First() and (alternately) the default when using .FirstOrDefault().
The problem is, I know it should be returning the number "4500" as I've run the query in SQL to see what should be there.
Any ideas on why it would be doing this?
I've searched high and low, but I can't find anyone else who has had this problem where they know it should be returning a value.
Code:
short? `shorty = db.sp_GetMaxLength("ApplicantEssay").First();`
The result of the SQL query used in the stored procedure:
Thanks so much for any assistance you can provide!!
Edit:
The only other code involved is the ADO.Net Entity auto-generated code.
At least, it's the only other code that the program steps through when I tried to examine what was going on.
I had a hard time looking at the return and trying to figure it out, but obviously it's returning nothing):
public virtual ObjectResult<Nullable<short>> sp_GetMaxLength(string cOLUMN_NAME)
{
var cOLUMN_NAMEParameter = cOLUMN_NAME != null ?
new ObjectParameter("COLUMN_NAME", cOLUMN_NAME) :
new ObjectParameter("COLUMN_NAME", typeof(string));
return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction<Nullable<short>>("sp_GetMaxLength", cOLUMN_NAMEParameter);
}
Edit #2: I guess I should close this question out.
I messed around with some stuff in sql, then put it back to what I had in the first place and re-executed the stored procedure. Following that, I deleted the Entity Model, reset web.config to its original state pre-model, closed Visual studio, re-opened Visual Studio, and then re-added an ADO.Net Entity Model to the project. I then re-ran the code, stepped through it, and then all of a sudden, "4500" popped up as the returned value.
I am completely flummoxed, since all the code is exactly the same without changes, but I guess that's the power of scrapping and re-starting??? No other explanation, though I hate when it's as simple as that. :-(
Thanks to all who commented. :-)
I'm trying to implement Microsoft Synchronization services into a smart device application I am developing however I seem to have hit a brick wall and I am hoping someone will be able to provide a solution. I have managed to implement synchronization so that it downloads every record in a table, however I am wanting to filter the records so only the data relating to the user is downloaded. To achieve this I have added the a WHERE Operator.kde = #kde clause to the SelectIncrementalInsertsCommand, as shown in the following code.
this.SelectIncrementalInsertsCommand.CommandText = #"IF #sync_initialized = 0 SELECT dbo.Operator.[OperatorID], [kde], [OperatorName], [Pass] FROM dbo.Operator LEFT OUTER JOIN CHANGETABLE(CHANGES dbo.Operator, #sync_last_received_anchor) CT ON CT.[OperatorID] = dbo.Operator.[OperatorID] WHERE dbo.Operator.[kde] = #kde AND (CT.SYS_CHANGE_CONTEXT IS NULL OR CT.SYS_CHANGE_CONTEXT <> #sync_client_id_binary) ELSE BEGIN SELECT dbo.Operator.[OperatorID], [kde], [OperatorName], [Pass] FROM dbo.Operator JOIN CHANGETABLE(CHANGES dbo.Operator, #sync_last_received_anchor) CT ON CT.[OperatorID] = dbo.Operator.[OperatorID] WHERE dbo.Operator.[kde] = #kde AND (CT.SYS_CHANGE_OPERATION = 'I' AND CT.SYS_CHANGE_CREATION_VERSION <= #sync_new_received_anchor AND (CT.SYS_CHANGE_CONTEXT IS NULL OR CT.SYS_CHANGE_CONTEXT <> #sync_client_id_binary)); IF CHANGE_TRACKING_MIN_VALID_VERSION(object_id(N'dbo.Operator')) > #sync_last_received_anchor RAISERROR (N'SQL Server Change Tracking has cleaned up tracking information for table ''%s''. To recover from this error, the client must reinitialize its local database and try again',16,3,N'dbo.Operator') END ";
I have then declared the #kde parameter as follows.
this.SelectIncrementalInsertsCommand.Parameters.Add(new System.Data.SqlClient.SqlParameter("#kde", System.Data.SqlDbType.Int));
To pass in the parameter I have added the following line to the code responsible for initiating the synchronization.
syncAgent.Configuration.SyncParameters.Add(new SyncParameter("#kde", kde));
NOTE: the kde value is an integer that is passed into my sync method
Despite these filters being added, the synchronization process seems to be completely ignoring them and downloading all the data for every operator. I have investigated this issue online and my code seems identical to numerous tutorials I have read, however it still does not work as desired.
I am fairly new to Sync Services so if anyone could provide me with information and guidance to solving this issue I will be hugely grateful
Thank You in advance
have you tried this?
ADDING FILTER TO LOCAL DATABASE CACHE GENERATED SYNC
I would suggest you run SQL Profiler as well to see the actual commands being passed to SQL Server.
I managed to fix this problem, it turned out to be some "dirty" records on the database which for some reason were affecting synchronization. Once I deleted these records everything worked as it should.
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 7 years ago.
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I'm getting the following error whenever my code creates a DataTableReader from a valid DataTable Object:
"DataTableReader is invalid for current DataTable 'TempTable'."
The thing is, if I reboot my machine, it works fine for an undetermined amount of time, then dies with the above. The code that throws this error could have been working fine for hours and then: bang. you get this error.
It's not limited to one line either; it's every single location that a DataTableReader is used. Also, this error does NOT occur on the production web server - ever.
This has been driving me nuts for the best part of a week, and I've failed to find anything on Google that could help (as I'm pretty positive this isn't a coding issue).
Some technical info:
DEV Box:
Vista 32bit (with all current windows updates)
Visual Studio 2008 v9.0.30729.1 SP
dotNet Framework 3.5 SP1
SQL Server:
Microsoft SQL Server 2005 Standard Edition- 9.00.4035.00 (X64)
Windows 2003 64bit (with all current windows updates)
Web Server:
Windows 2003 64bit (with all current windows updates)
Any help, ideas, or advice would be greatly appreciated!
UPDATE 1:
Ok - Have tried the following now with no success:
1: Rebooted
2: SFC / ScanNow
3: Changed SQL Servers
4: Tried a different method that uses DataTableReaders
5: Cleaned solution
The only thing I did find that worked was copy & pasting the code
from the main Visual studio instance, into another which had a simple console app.
This then worked as expected (queried database and got results into a dataTable, created a datatablereader on that table, then queried hasrows before calling .Read()...
All of which worked.
I am struggling to see what could cause this, as there are NO code faults - i'm 100% certain, as it runs perfectly when published to the webserver.
I think using the while(reader.read()) may solve your problem.
if (myReader.HasRows)
while (myReader.Read())
Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));
else
Console.WriteLine("No rows returned.");
myReader.Close();
UPDATE:
Also from msdn:
The HasRows property returns information about the current result set. If the DataTableReader contains multiple result sets, you can examine the value of the HasRows property immediately after you call the NextResult method in order to determine whether the new result set contains rows.
Use the HasRows property to avoid the requirement to call the Read method of the DataTableReader if there are no rows within the current result set.
DataTableReader.HasRows Property
Had the same problem and got rid of it after clearing the variables in the watch window.
Clearing the watch window & doing rebuilds worked for me. However, because I had to remember to frequently rebuild, I eventually just renamed it also. (prior to renaming, adding additional watch variables on an object could cause previous watch variables on that object to become invalid -- even without progressing through the code, ie staying on the same line)
Wrap usage of DataTableReader (and all IDisposables) with using.
OK.. Further down in the code, I have the following code:
using (DataTableReader tr = dtCustomers.CreateDataReader())
{
....
}
If I change this to read:
using (DataTableReader tr2 = dtCustomers.CreateDataReader())
{
....
}
Then, and remember this bit of code is much later down in the same procedure, BOTH bits of code work without fault!
So, this doesn't work:
using (DataTableReader tr = dt.CreateDataReader())
{
...
}
....
using (DataTableReader tr = dt.CreateDataReader())
{
...
}
But this does:
using (DataTableReader tr = dt.CreateDataReader())
{
...
}
....
using (DataTableReader tr2 = dt.CreateDataReader())
{
...
}
I don't understand why this way works, but it does and as I've not had another answer, I'll be going with this.
If you know why this works, and why the original doesn't, please can you enlighten me? :)
Just thought I would post on here in case it's helps someone else. I tried a number of things and in the end i simply changed the name of the datareader and it worked, kind of similar to here. i dont know why for sure but i think it might be because the datareader (originally) wasnt being closed, so maybe after a few times debugging, there was lots of "stuff" in memory with a certain name attached and it said "no more!". still, i could be talking bullpies. my advice, change the name of your datareader variable and make sure you close it after you use it
Seems like a bug on getting the tableReader... i have code that has been working for ears and if i change another method sometimes i get that errro... some times it's solved just recompiling (rebuild), another times i reinstalled the .NET framework or use the option repair of it... i am starting to put try catch sections to use the reader if the system "wants" to givme the reader and the DataTable if not.
Greetings.