Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Finally it will looks like:
... your code
int DB = -1; // database identifier//---
... your code
intOnInit()
{
DB = MySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag);
if (DB != -1)
{
// connection succeeded!// here you have to define table creation logic
}
return(INIT_SUCCEEDED);
}
voidOnDeinit(constint reason)
{
MySqlDisconnect(DB);
}
voidOnTick()
{
// first command:if (DB==-1) return; // do not any action when no connection// here your code without cMySqlConnect call
}
You have to rebuild your code based on the requirements of project, as I see the currently there is no clear logic, everything messed up.
Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Finally it will looks like:
I changed step by step, but the problem is still exist when use the expert in one mt4 for four or more symbols. it print " Access violation read to 0x0000000B in '...MQLMySQL.dll' "
the code is followed
<--
#include <MQLMySQL.mqh>
int MySqlErrorNumber; // recent MySQL error number
Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Finally it will looks like:
The problem is it can't use in one mt4 for more than two symbols, if use in only one symbol, it's normal. When use in four or more, it's run fine, but after a few minutes, it prints the problem"Access violation read to 0x0000000B in '...MQLMySQL.dll'"
The exambles is all scripts, it's run only one times, You may try one experts call the dll in four or more symbols in one or two mt4, You may find the problem.
Would be the dll needs a memeoy release or garbe collection?
MFC dumps leaks prematurely whenit exits, instead of waiting for the CRT to dump leaks following static data destruction, and this causes spurious leak reports for objects which allocated memory before MFC was initialized and which thus are destroyed after MFC exits. This is commonly observed when using the MFC DLL in a program that also uses the C++ runtime DLL.
Based on the code you have provided I guess you are new to MQL.
I'm sorry, I have no time to teach you, but I have time for testing the software I've developed.
So, here are logs attached. I have running 2 accounts within 6 and 5 charts concurrently.
Have build testing EA for you, based on your logic: each table defined for each currency pair and can keep the online market data for different accounts.
You can inspect the logs, no one error "Access violation..." was raised.
The problem is not in MQLMySQL library.
Testing EA:
//+------------------------------------------------------------------+//| DFTest.mq4 |//| Copyright 2014, MetaQuotes Software Corp. |//| http://www.mql5.com |//+------------------------------------------------------------------+#property copyright"Copyright 2014, MetaQuotes Software Corp."#property link"http://www.mql5.com"#property version"1.00"#property strict#include <MQLMySQL.mqh>
inputstring Host = "localhost";
inputstring User = "root";
inputstring Password = "ioctrl";
inputstring Database = "mysql";
inputint Port = 3306;
inputstring Socket = "";
inputint ClientFlag = 0;
inputint Timer = 1; // Timer (seconds) not used nowint DB;
intOnInit()
{
SQLTrace = true; // to see all the queries would be send to the databaseEventSetTimer(Timer);
DB = MySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag);
if( DB == -1 )
{
Print("Database is not connected! Error: ", MySqlErrorDescription);
return (INIT_FAILED);
}
// create table if not existsstring cmd;
cmd = "CREATE TABLE IF NOT EXISTS `" + Symbol() + "` (id int NOT NULL AUTO_INCREMENT PRIMARY KEY, AccountNumber int, "
+ "Symbol char(20), Bid double, Ask double, Spread double, "
+ "Memo char(50), "
+ "Time datetime) ENGINE=MEMORY DEFAULT CHARSET=utf8";
if (!MySqlExecute(DB, cmd))
{
Print ("Table creation error: ",MySqlErrorDescription);
return (INIT_FAILED);
}
return(INIT_SUCCEEDED);
}
voidOnDeinit(constint reason)
{
MySqlDisconnect(DB);
EventKillTimer();
}
voidOnTimer()
{
// you should never call OnTick from OnTimer and vice versa.// the target of these 2 functions is different
}
voidOnTick()
{
int account;
string symbol;
double spread;
string Query, cmd;
int Cursor;
int Rows;
if (DB == -1)
{
Comment("Database is not connected ... ");
return;
}
if ( IsExpertEnabled() && IsConnected() && AccountNumber() > 0 )
{
account = AccountNumber();
symbol = "`"+Symbol()+"`"; // if you have to use it as table name you have to use quotes as a good practice for MySQL database
spread = (Ask - Bid);
// possible it could be better to use something like this: admission = MarketInfo(symbol, MODE_SPREAD);
Query = "SELECT * FROM " + symbol + " where AccountNumber = " + (string)account;
Cursor = MySqlCursorOpen(DB, Query);
if (Cursor >= 0)
{
Rows = MySqlCursorRows(Cursor);
if ( Rows > 0 )
{
cmd = "update " + symbol + " set Bid = "+(string)Bid + ", Ask = " + (string)Ask
+ ", Spread = " + DoubleToStr(spread, Digits)
+ ", Time = '" + TimeToString(TimeLocal(), TIME_DATE|TIME_SECONDS) +"' where AccountNumber = " + (string)account;
}
else
{
cmd = "INSERT INTO " + symbol + "(AccountNumber, Symbol, Bid, Ask, Spread, Memo, Time) VALUES ("
+ (string)account + ", \'" + symbol + "\', "+DoubleToStr(Bid,Digits)+","+ DoubleToStr(Ask,Digits) + "," + DoubleToStr(spread, Digits)
+ ", \'" + AccountCompany() +"\', \'"+TimeToString(TimeLocal(), TIME_DATE|TIME_SECONDS)+"\')";
}
if (!MySqlExecute(DB, cmd))
{
Print("Updating error: ",MySqlErrorDescription);
Print (cmd);
}
MySqlCursorClose(Cursor);
}
}
}
This is right logic of using the library.
Due to optimization you can even do not use SELECT statement, just execute UPDATE statement , than check if (MySqlRowsAffected()==0) means no one row was updated and needs INSERT, so apply the INSERT statement.
You have ~100% of updates, so this workaround can increase the performance and reduce network traffik.
And at the end, full source codes of project (include DLL development) has been attached to the article, you may change it on your own way.
If you fill that the problem in MqlMySQL.DLL anyway, you can debug it and fix for yourself.
Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Finally it will looks like:
Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Finally it will looks like:
Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Finally it will looks like:
I changed step by step, but the problem is still exist when use the expert in one mt4 for four or more symbols. it print " Access violation read to 0x0000000B in '...MQLMySQL.dll'
"
the code is followed
<--
#include <MQLMySQL.mqh>
int MySqlErrorNumber; // recent MySQL error number
string MySqlErrorDescription; // error description
//+------------------------------------------------------------------+
//| Expert initialization function |
//+------------------------------------------------------------------+
int OnInit()
{
EventSetTimer(timeSeconds);
DB = MySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag);
if( DB == -1 )
{
Print("Database is not connected ... ");
}
return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Expert deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
MySqlDisconnect(DB);
EventKillTimer();
ObjectsDeleteAll();
}
void OnTimer()
{
//Alert(TimeCurrent());
OnTick();
}
//+------------------------------------------------------------------+
//| Expert tick function |
//+------------------------------------------------------------------+
void OnTick()
{
if( DB == -1 )
{
Alert("Database is not connected ... ");
return;
}
if( IsExpertEnabled() && IsConnected() && AccountNumber() > 0 && DB != -1 )
{
int account = AccountNumber();
string symbol = Symbol();
if( cmd != "" && cmd != NULL )
{
symbol = cmd;
}
symbolOrder = symbol + "_table";
double spread = (Ask - Bid);
admission = spread*MathPow(10, Digits);
//int DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag);
Query = "SELECT * FROM " + symbol + " where AccountNumber = " + (string)AccountNumber();
//Print(Query);
int Cursor1 = MySqlCursorOpen(DB, Query);
if (Cursor1 >= 0)
{
int Rows1 = MySqlCursorRows(Cursor1);
int dataRows1 = Rows1;
//Alert(dataRows);
if( dataRows1 > 0 )
{
Query = "update " + symbol + " set Bid = "+(string)Bid + ", Ask = " + (string)Ask
+ ", Spread = " + DoubleToStr(spread, Digits)
+ ", Time = '" + TimeToString(TimeLocal(), TIME_DATE|TIME_SECONDS) +"' where AccountNumber = "
+ (string)account; // + "' and Symbol = '" + symbol +"'";
MySqlExecute(DB, Query);
MySqlCursorClose(Cursor1);
}
else if( dataRows1 == 0 )
{
Query = "CREATE TABLE IF NOT EXISTS " + symbol + " (id int NOT NULL AUTO_INCREMENT PRIMARY KEY, AccountNumber int, "
+ "Symbol char(20), Bid double, Ask double, Spread double,"
+ "Memo char(50), "
+ "Time datetime)ENGINE=MEMORY DEFAULT CHARSET=utf8 ";
MySqlExecute(DB, Query);
Query = "INSERT INTO " + symbol + "(AccountNumber, Symbol, Bid, Ask, Spread, Memo, Time) VALUES ("
+ (string)account + ", '" + symbol + "', "+(string)Bid+","+ (string)Ask + ","
+ DoubleToStr(spread, Digits)
+ ", '" + (string)AccountCompany()
+"', \'"+TimeToString(TimeLocal(), TIME_DATE|TIME_SECONDS)+"\')";
if(MySqlExecute(DB, Query) != true )
{
//Query = "DROP TABLE IF EXISTS `data_table`";
//MySqlExecute(DB, Query);
Query = "CREATE TABLE IF NOT EXISTS " + symbol + "(id int NOT NULL AUTO_INCREMENT PRIMARY KEY, AccountNumber int, "
+ "Symbol char(20), Bid double, Ask double, Spread double,"
+ "Memo char(50), "
+ "Time datetime)ENGINE=MEMORY DEFAULT CHARSET=utf8 ";
MySqlExecute(DB, Query);
}
}
MySqlCursorClose(Cursor1); // NEVER FORGET TO CLOSE CURSOR !!!
}
}
}
-->
Ok, I see you have wrote an expert advisor for this purposes, and it is written without recommendations I've posted in article.
So, let's move step by step:
1. The calling of " DB = cMySqlConnect(Host, User, Password, Database, Port, Socket, ClientFlag); " should be made inside OnInit() standard function instead of OnTick().
2. You are uses cMySqlConnect - it's imported function form DLL, you have to use MySqlConnect function instead of cMySqlConnect function !
3. You have to call MySqlDisconnect function inside OnDeinit() stundard function.
4. You have to check database connection identifier inside OnTick() standard function to be sure that connect was successful.
Finally it will looks like:
The problem is it can't use in one mt4 for more than two symbols, if use in only one symbol, it's normal. When use in four or more, it's run fine, but after a few minutes, it prints the problem"Access violation read to 0x0000000B in '...MQLMySQL.dll'"
The exambles is all scripts, it's run only one times, You may try one experts call the dll in four or more symbols in one or two mt4, You may find the problem.
Would be the dll needs a memeoy release or garbe collection?
CRT to dump leaks following static data destruction, and this causes
spurious leak reports for objects which allocated memory before MFC
was initialized and which thus are destroyed after MFC exits. This is
commonly observed when using the MFC DLL in a program that also uses
the C++ runtime DLL.
Hello once again.
Based on the code you have provided I guess you are new to MQL.
I'm sorry, I have no time to teach you, but I have time for testing the software I've developed.
So, here are logs attached. I have running 2 accounts within 6 and 5 charts concurrently.
Have build testing EA for you, based on your logic: each table defined for each currency pair and can keep the online market data for different accounts.
You can inspect the logs, no one error "Access violation..." was raised.
The problem is not in MQLMySQL library.
Testing EA:
This is right logic of using the library.
Due to optimization you can even do not use SELECT statement, just execute UPDATE statement , than check if (MySqlRowsAffected()==0) means no one row was updated and needs INSERT, so apply the INSERT statement.
You have ~100% of updates, so this workaround can increase the performance and reduce network traffik.
And at the end, full source codes of project (include DLL development) has been attached to the article, you may change it on your own way.
If you fill that the problem in MqlMySQL.DLL anyway, you can debug it and fix for yourself.
Best wishes,
Eugene
干得好，非常感谢Eugeniy。
你的代码帮了我大忙，让我节省了很多时间。我试着成功进行了 INSERT、SELECT、UPDATE 和 DELETE 查询。如果我没记错的话，"光标 "是否只适用于 SELECT 查询？
= pedma
干得好，非常感谢Eugeniy。
你的代码帮了我大忙，让我节省了很多时间。我试着成功进行了 INSERT、SELECT、UPDATE 和 DELETE 查询。如果我没记错的话，"光标 "是否只适用于 SELECT 查询？
= pedma
没错！
游标只用于数据选择，因为我们必须将数据从数据库接收到 MQL 变量中，而不仅仅是向数据库发送 sql 命令。
很高兴我的解决方案能帮到你。
祝你好运
尤金
你好，尤金、
我想知道你是否还在做有偿开发项目，因为我想创建一个远程交易复制器，集成到我将要销售的 EA 中。
我在 Upwork 上看了一下，您最近似乎没有完成任何自由职业者项目。
我自己用你创建的库做过一次，但结果不太好。不过我相信，对你这样有编程能力的人来说，这很容易！
在此先表示感谢、
詹姆斯
你好，尤金、
我想知道你是否还在做有偿开发项目，因为我想创建一个远程交易复制器，集成到我将要销售的 EA 中。
我在 Upwork 上看了一下，您最近似乎没有完成任何自由职业者项目。
我自己用你创建的库做过一次，但结果不太好。不过我相信，对你这样有编程能力的人来说，这很容易！
在此先表示感谢、
詹姆斯
你好，詹姆斯、
我现在只在 Upwork 做一个大项目。所以，现在没有什么空闲时间。你在程序库方面有什么问题？我能帮上什么忙？