simple mysql wrapper - page 2

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I'm not much of a C++ expert. In the zip is the full tree of the "project" created in visual studio. In VS I just used the compile command to get the DLL. Please take from there...I'm afraid I can't give any pointers on other building methods or Make files.


Russell

 

Russell


many many thanks. I have now the db working.

 
OK thanks, I was confused by the project file extension - I'm using visual C++ 2008 express edition which uses .vcproj for it's project file extensions - but it can read the earlier version project file. Are you sure you posted your latest source file ? I found I had to add: row[i].len = strlen(row[i].string); after line #52 of mysql_wrapper.cpp (i.e. after row[i].string = lrow[i]; ) in order to get any data back from the database into my mq4 code.
 
I also found I had to comment out the calls to mysql_free_result() in MySQL_FetchRow() in mysql.mqh in order for the strings from the database query to still be available when control was returned to my mq4 code. Maybe it would be a good idea to change the local variable liResult to a global variable (say giResult) in mysql.mqh and have a seperate function (say MySQL_FreeResult()) to do the call to mysql_free_result() when the user has finished with the strings so that they persist for as long as the user requires them.
 
gc1:
OK thanks, I was confused by the project file extension - I'm using visual C++ 2008 express edition which uses .vcproj for it's project file extensions - but it can read the earlier version project file. Are you sure you posted your latest source file ? I found I had to add: row[i].len = strlen(row[i].string); after line #52 of mysql_wrapper.cpp (i.e. after row[i].string = lrow[i]; ) in order to get any data back from the database into my mq4 code.

Thanks for the feedback! The code posted worked for me. On review kind a strange it did. 8-) I adjusted the code as suggested.

Files:
mysql_wrapper_v1.0.2.zip  1094 kb
 
I have found a small problem. On my system if MySQL_FetchRow() is called with a SQL SELECT command that returns an empty set (i.e. no data matches the select clause) then this crashes the terminal. Including some code in MySQL_FetchRow() to call mysql_num_rows() and only call MT4_mysql_fetch_row() if there is 1 or more row(s) of data seems to fix this.
 

Thanks! Small update as suggested attached


Russell

Files:
mysql_v2.0.2.mqh  5 kb
 
Is there are any 64 bit version of this or can you provide instructions on how to recompile the project file to a 64 bit version?
 

MT4_mysql_fetch_row  crashes the terminal in vista 


 string lsQuery = "SELECT * FROM `symbols`";

   MySQL_FetchArray(lsQuery, lsSymolData); 

crush

          err=mysql_errno(giMySQL); if(err>0){Print(AccountServer()+ " Ошибка в getsymbol() функция MySQL_FetchArray() err # "+err+" "+mysql_error(giMySQL) );return(err);}

   for (int i = 0; i < ArrayRange(lsSymolData,0); i++){

      for (int j = 0; j < ArrayRange(lsSymolData,1); j++){

        // Print(i+","+j+": "+lsSymolData[i][j]);

      }

   }


table symbols:


id symbols

1 EURUSD

2 GBPUSD

3 GBPJPY


please fix it..

 

MySQL_FetchArray() crashes my terminal too.. I've no idea about why could it be, any ideas?

Edit: Solved it by taking the "lsResult" variable outside of the function and passing it as parameter. I pass newly created variable each time I need to fetch different number of fields (as terminal crashes on ArrayResize(lsResult, ..) if function was already called at least once and fetched another number of fields previously).

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