Preamble: This question may be useful to people who get wrong error messages when using MySQL. Proof is given that the error message is wrong.
In a MySQL database (version 5.7.18), MyISAM table "sensorhistory" has a column "id" of type "int(11)" with Extra "auto_increment". Data are inserted from an application written in C#. The INSERT query does NOT write the id column directly, of course. That's what the "auto_increment" is for. The table contains further 30 fields of float and varchar types, resp., plus a DateTime(3). The parameterized query is long.
I receive following error message:
Duplicate entry '284093' for key 'PRIMARY'
at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int64& insertedId)
at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)
at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()
at DataStorage.SensorHistoryDatastore.StoreSensorHistory(IReadOnlyList'1 _reports, Boolean _canRetry) in C:\Users\bernhard.hiller\SVN\Product-SW\trunk\C_DataStorage\PhysicalContainers\SensorHistoryDatastore.cs:line 84
Oddly, when I execute SELECT max(id) FROM sensorhistory in MySQL Workbench, I get a maximum value of 284092, i.e. 1 less than the "duplicate entry". That is proof that the error message is wrong.
I'd like to know how such an odd error can occur, and how to fix it.
Addendum:
An "Analyze table" in MySQL Workbench showed that the table is corrupt:
Found key at page 6585344 that points to record outside datafile
It could be repaired with a simple Repair table sensorhistory
I am still interested in how that corruption of the table can have occured.
By the way: a big THANK YOU to all those DOWNVOTERS who seem to be unable to read the text: this is not a f***ing stupid question about a "duplicate key", because I showed proof that the duplicate value does not exist at all!
Addendum 208-09-12:
The error re-occured after just 1 day, same table, same error message (just with a new value).
The Windows Eventlog showed more than 7 crashes between Sep 7 and Sep 11 (id 6008: "The previous system shutdown was unexpected"). The newest entry in the table sensorhistory was shortly before such crash in both cases.
The crashes ended on Sep 11 in the morning. I do not know the reason - other people are working on that test machine too. There were no more database issues then.
I conclude that a sudden Windows crash caused some inconsistency in the database, which then lead to that error message.
I have an intermittent Devart.Data.Linq.ChangeConflictException: Row not found or changed raising it's ugly head. The funny thing is, the change is still written to the database!
The stack trace says:
Devart.Data.Linq.ChangeConflictException: Row not found or changed.
at Devart.Data.Linq.Engine.b4.a(IObjectEntry[] A_0, ConflictMode A_1, a A_2)
at Devart.Data.Linq.Engine.b4.a(ConflictMode A_0)
at Devart.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode)
at Devart.Data.Linq.DataContext.SubmitChanges()
at Billing.Eway.EwayInternal.SuccessCustomerRenewal(String username, Bill bill, EwayTransaction transaction) in c:\Users\Ian\Source\Repos\billing-class-library\Billing\Billing\Eway\EwayInternal.cs:line 552
at Billing.Eway.Eway.BillAllUsers() in c:\Users\Ian\Source\Repos\billing-class-library\Billing\Billing\Eway\Eway.cs:line 138
And my code for Billing.Eway.EwayInternal.SuccessCustomerRenewal:
internal static void SuccessCustomerRenewal(string username, Bill bill, EwayTransaction transaction)
{
// Give them their points!
ApplyBillToCustomerAccount(username, bill, true);
BillingEmail.SendRenewalSuccessEmail(username, bill, transaction);
using (MsSqlDataClassesDataContext msSqlDb = new MsSqlDataClassesDataContext())
{
// TODO: Remove this logging
msSqlDb.Log = new StreamWriter(#"logs\db\" + Common.GetCurrentTimeStamp() + "-MsSQL.txt", true) { AutoFlush = true };
EwayCustomer ewayCustomer = msSqlDb.EwayCustomers.First(c => c.Username == username);
ewayCustomer.NextBillingDate = Common.GetPlanExpiry(bill.BillPlan);
using (MySqlDataContext mySqlDb = new MySqlDataContext())
{
// TODO: Remove this logging
mySqlDb.Log = new StreamWriter(#"logs\db\" + Common.GetCurrentTimeStamp() + "-MySQL.txt", true) { AutoFlush = true };
BillingMySqlContext.Customer grasCustomer = mySqlDb.Customers.First(c => c.Username == username);
// Extend their membership date out so that the plan doesn't expire because of a failed credit card charge.
grasCustomer.MembershipDate =
ewayCustomer.NextBillingDate.AddDays(1);
mySqlDb.SubmitChanges(); // <-- This is line 552
}
msSqlDb.SubmitChanges();
}
}
I know that the issue occurs on the mySqlDb.SubmitChanges() line, since that DB context is the one using Devart (Linq solution for MySQL databases): the other context uses pure MS Linq.
Not only is the change written to the MySql DB (inner using block), but it is also written to the MsSql DB (outer using block). But that's where the magical success ends.
If I could I would write a Minimal, Complete and Verifiable example, but strangely I'm unable to generate a Devart ChangeConflictException.
So, why does the change get saved to the database after a Devart.Data.Linq.ChangeConflictException? When I previously encountered System.Data.Linq.ChangeConflictException changes weren't saved.
Edit 1:
I've also now included the .PDB file and gotten line number confirmation of the exact source of the exception.
Edit 2:
I now understand why I can't generate a ChangeConflictException, so how is it happening here?
These are the attributes for MembershipDate:_
[Column(Name = #"Membership_Date", Storage = "_MembershipDate", CanBeNull = false, DbType = "DATETIME NOT NULL", UpdateCheck = UpdateCheck.Never)]
I know I can explicitly force my changes through to override any potential conflict, but that seems undesirable (I don't know what I would be overriding!). Similarly I could wrap the submit in a try block, and retry (re-reading each time) until success, but that seems clunky. How should I deal with this intermittent issue?
Edit 3:
It's not caused by multiple calls. This function is called in one place, by a single-instance app. It creates log entries every time it is run, and they are only getting created once. I have since moved the email call to the top of the method: the email only gets sent once, the exception occurs, and database changes are still made.
I believe it has something to do with the using blocks. Whilst stepping through the debugger on an unrelated issue, I entered the using block, but stopped execution before the SubmitChanges() call. And the changes were still written to the database. My understanding was that using blocks were to ensure resources were cleaned up (connections closed, etc), but it seems that the entire block is being executed. A new avenue to research...
But it still doesn't answer how a ChangeConflictException is even possible given Devart explicitly ignores them.
Edit 4:
So I wasn't going crazy, the database change did get submitted even after I ended execution in the middle of the using block, but it only works for websites.
Edit 5:
As per #Evk's suggestion I've included some DB logging (and updated the stacktrace and code snippet above). The incidence rate of this exception seems to have dropped, as it has only just happened since I implemented the logging. Here are the additional details:
Outer (MS SQL) logfile:
SELECT TOP (1) [t0].[id], [t0].[Username], [t0].[TokenId], [t0].[PlanId], [t0].[SignupDate], [t0].[NextBillingDate], [t0].[PaymentType], [t0].[RetryCount], [t0].[AccountStatus], [t0].[CancelDate]
FROM [dbo].[EwayCustomer] AS [t0]
WHERE [t0].[Username] = #p0
-- #p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [dyonis]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.18408a
(It just shows the SELECT call (.First()), none of the updates show).
Inner (MySQL) logfile:
SELECT t1.Customer_ID, t1.Username, t1.Account_Group, t1.Account_Password, t1.First_Name, t1.Last_Name, t1.Account_Type, t1.Points, t1.PromoPoints, t1.Phone, t1.Cell, t1.Email, t1.Address1, t1.Address2, t1.City, t1.State, t1.Country, t1.Postcode, t1.Membership_Group, t1.Suspend_On_Zero_Points, t1.Yahoo_ID, t1.MSN_ID, t1.Skype_ID, t1.Repurchase_Thresh, t1.Active, t1.Delete_Account, t1.Last_Activity, t1.Membership_Expires_After_x_Days, t1.Membership_Date, t1.auth_name, t1.created_by, t1.created_on, t1.AccountGroup_Points_Used, t1.AccountGroup_Points_Threashold, t1.LegacyPoints, t1.Can_Make_Reservation, t1.Gallery_Access, t1.Blog_Access, t1.Private_FTP, t1.Photometrica, t1.Promo_Code, t1.Promo_Expire_DTime, t1.Gift_FirstName, t1.Gift_LastName, t1.Gift_Email, t1.Gift_Phone, t1.Gift_Active, t1.NoMarketingEmail, t1.Can_Schedule, t1.Refered_By, t1.Q1_Hear_About_Us, t1.Q2_Exp_Level, t1.Q3_Intrests, t1.GIS_DTime_UTC, t1.Membership_Expire_Notice_Sent, t1.Promo_Expire_Notice_Sent, t1.isEncrypted, t1.PlanId
FROM grasbill.customers t1
WHERE t1.Username = :p0 LIMIT 1
-- p0: Input VarChar (Size = 6; DbType = AnsiString) [dyonis]
-- Context: Devart.Data.MySql.Linq.Provider.MySqlDataProvider Mapping: AttributeMappingSource Build: 4.4.519.0
UPDATE grasbill.customers SET Membership_Date = :p1 WHERE Customer_ID = :key1
-- p1: Input DateTime (Size = 0; DbType = DateTime) [8/3/2016 4:42:53 AM]
-- key1: Input Int (Size = 0; DbType = Int32) [7731]
-- Context: Devart.Data.MySql.Linq.Provider.MySqlDataProvider Mapping: AttributeMappingSource Build: 4.4.519.0
(Shows the SELECT and UPDATE calls)
So the log files don't really give any clue as to what's happening, but again the MS SQL database has been updated! The NextBillingDate field has been set correctly, as per this line:
ewayCustomer.NextBillingDate = Common.GetPlanExpiry(bill.BillPlan);
If it hadn't been updated, the user would have been billed again on the next timer tick (5 mins later), and I can see from logging that didn't happen.
One other interesting thing to note is the log file timestamps. As you can see from the code above I grab the current (UTC) time for the log filename. Here is the information shown by Windows File Explorer:
The MS SQL logfile was created at 04:42 (UTC) and last modified at 14:42 (UTC+10, Windows local-time), but the MySQL logfile was last modified at 15:23 (UTC+10), 41 minutes after it was created. Now I assume the logfile StreamWriter is closed as soon as it leaves scope. Is this delay an expected side effect of the exception? Did it take 41 minutes for the garbage collector to realise I no longer needed a reference to the StreamWriter? Or is something else going on?
Well 6 months later I finally got to the bottom of this problem. Not sure if it will ever help anyone else, but I'll detail it anyway.
There were 2 problems in play here, and 1 of them was idiocy (as they usually are), but one was legitimately something I did not know or expect.
Problem 1
The reason the changes were magically made to the database even though there was an exception was because the very first line of code in that function ApplyBillToCustomerAccount(username, bill, true); updates the database! <facepalm>
Problem 2
The (Devart) ChangeConflictException isn't only thrown if the data has changed, but also if you're not making any changes. MS SQL stores DateTimes with great precision, but MySQL (or the one I'm running at least) only stores down to seconds. And here's where the intermittency came in. If my database calls were quick enough, or just near the second boundary, they both got rounded to the same time. Devart saw no changes to be written, and threw a ChangeConflictException.
I recently made some optimisations to the database which resulted in far greater responsiveness, and massively increased incidence of this exception. That was one of the clues.
Also I tried changing the Found Rows parameter to true as instructed in the linked Devart post but found it did not help in my case. Or perhaps I did it wrong. Either way now that I've found the source of the issue I can eliminate the duplicate database updates.
This may not actually be a code issue, but here goes...
My C# program reads a CSV file and builds an SQL Insert statement to insert all rows of the file into a table, so the Insert statement becomes:
Insert GHP_For_CMS (GroupId, EmployeeID, etc...) values (rec1_field1, rec1_field2, etc...), (rec2_field1, rec2_field2, etc...)
SQL runs flawlessly against a Sandbox/Dev db from a Dev Server. SQL crashes with a NullReference exception ("Object not set to an instance of an object") against the same Sandbox/Dev db from a Production server. The Dev server has Framework version 4.0.30319.18052, and the Production has Framework version 4.0.30319.18063.
I know I haven't given a lot of information here, but anyone have any ideas? Or at least ideas of something to check? I've been banging my head against this one for 3-4 days and nothing is rearing it's ugly head.
TIA!
The error happens on the 'ExecuteNonQuery' below...
string dbConnString = ConfigurationManager.ConnectionStrings[targetDatabase].ToString();
if (null != dbConnString)
{
using (SqlConnection dbConn = new SqlConnection(dbConnString))
{
if (dbConn != null)
{
SqlCommand cmd = new SqlCommand(m_sqlInserts.ToString(), dbConn);
dbConn.Open();
int rowsAdded = cmd.ExecuteNonQuery();
...
So the answer to the question (because I couldn't post more details and I really wanted to know of things to try): is that it's a simple Permissions issue with the account that is running the process not being able to insert records to the table. The comment that helped me get to that conclusion came from #cdonner (Thank you, again!) in wanting to see a stack trace. I realized that I could return a StackTrace in the console log instead of just the InnerException message and it (the SQL Error) was finally revealed.
I am trying to use a parametrized query to create an index on our Oracle server. I can create the index fine if I use string concatenation, so I believe its not an account or permissions issue. I get the error:
ORA-01036: illegal variable name/number
I can not find any error in the code, but I am sure I am missing something. I am using Oracle.DataAccess.dll version 4.112.3.0. The version the server reports is "Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production"
I have tried removing all the params, except one and get the same error. Any combination of 1 or more params causes the error. The error happens every time without fail. I have used watches to verify that the params are correctly getting set, and I have tried clearing the params before setting. No matter what I do so far, I still get the error. Here is the code:
using (OracleCommand mycom = new OracleCommand())
{
using (OracleConnection Connection = new OracleConnection(connectionString))
{
mycom.BindByName = true;
mycom.CommandText = "CREATE INDEX :indexname on :tablename (:colname)";
mycom.Parameters.Add("indexname", indexName);
mycom.Parameters.Add("tablename", tableName);
mycom.Parameters.Add("colname", colName);
mycom.Connection = Connection;
mycom.CommandType = CommandType.Text;
mycom.Connection.Open();
mycom.ExecuteNonQuery();
}
}
You cannot use bind variables in a DDL statement (like CREATE INDEX). Bind variables are only used in DML statements. You would need to build up the DDL statement in your C# code.
Is this a part of the installation process for your application? Otherwise, it would be exceedingly unusual to want to create an index from an application. Your application shouldn't be creating any database objects outside of the initial installation process.
I know it was 1000000000 times already, but none solution helped to me.
I want to insert data in C# using OleDB. I tried mln solutions but here is the easiest one which should work but it doesn't:
SQLCONNECTION = #"Provider=Microsoft.Jet.OLEDB.4.0;DataSource=|DataDirectory|\dbScenariusz.mdb";
using (OleDbConnection connection = new OleDbConnection(SQLCONNECTION))
{
string sql = "INSERT INTO Table (content) VALUES('lala')";
connection.Open();
OleDbCommand command = new OleDbCommand(sql, connection);
command.ExecuteNonQuery();
connection.Close();
}
SQLCONNECTION is ok. It works fine for the SELECT query.
string sql - I tried this query in Access and it works fine.
I get no error. It just didn't insert anything to the database.
When I run the query in Access (the same database) the row is inserted.
The strange thing is that command.ExecuteNonQuery(); returns 1! That means that 1 row was affected!
I really have no idea where the problem is, so I really appreciate any help.
Sorry for my english.
UPDATE: Another strange thing. I change query to update and it works fine! really wtf? :)
You are connecting to the DataDirectory. Is the .mbd file being copied after the build? In other words are you re-deploying the database with each build and thereby losing the inserts?
A quick test could be using the same code and same connection to do a select after the insert.
In the solution Explorer, check app.config. Double click the app.config, then re-enter the connectionString. Give the path of your database.
For example, in my project the default location of connectionString is:
connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\App_Data\database.accdb;Persist Security Info=True"
Suppose the database is stored in this location:
C:\Documents and Settings\Amuk\My Documents\Visual Studio 2010\Projects\insertion\insertion\App_Data
therefore, replace the connectionString with
connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Documents and Settings\Amuk\My Documents\Visual Studio 2010\Projects\insertion\insertion\App_Data\database.accdb;Persist Security Info=True"
your problem will be solved, i hope this will definitely help you, i was also getting the same problem, and by replacing the connectionString with original path, the database is storing all records.
You can try to use transaction to commit your changes.
command.Transaction = connection.BeginTransaction(); //after connection.open()
Then add
command.Transaction.Commit(); //Before connection.close()