c# - Concurrent users on Application result in MySQL Database Error -

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i have c# web application connects mysql database. when multiple users access site @ same time see "there open datareader associated command must closed first" error. application works fine when 1 person accessing site.

i found multiple articles sited multipleactiveresultsets=true in connection string, applies sql server not mysql.

i traced error runsql function handles bulk of database queries unable find solution.

this straight forward function, takes raw sql code, list of parameters, enum translates 1 of many possible database connection strings, , bool determines if need set transaction.

i @ loss. 

public datatable runsql(string querystr, list<mysqlparameter> parameters, connectiontype connection, bool transaction) {     datatable results = new datatable();     mysqlconnection con = new mysqlconnection(getconnection(connection));     mysqltransation trans;     mysqlcommand command;      con.open();      //if transaction requested, tie 1 query     if(transaction)     {         trans = con.begintransaction();         command = new mysqlcommand(querystr, con, trans);     }     else     {         command = new mysqlcommand(querystr, con);     }      //if parameters provided add them query     if(parameters.count > 0)         foreach(mysqlparameter parm in parameters)             command.parameters.add(parm);      try     {         //send command , results         mysqlreader rdr = command.execurereader();          //populate column names         string columnname;         type type;         foreach(dataviewrow row in rdr.getschematable().defaultview)         {             columnname = row["columnname"].tostring();             type = (type)row["datatype"];             results.columns.add(columnname, type);         }          //populate results         results.load(rdr);          //so far good, close transaction if 1 requested         if(transaction)         {             command.transaction.commit();         }          con.close();     }     catch (exception up)     {         //something bad happened, rollback if there transaction         if(transaction)         {             command.transaction.rollback();         }          con.close();          //report error handling @ source.         throw up;     }      return results; }

concurrency in mysql nightmare. sorry start out this, if @ possible should port mssql since using c# , integrates easily.

concurrency poor when using myisam mysql database engine. first, , large red flag, myisam does not support transactions. means cannot change isolation levels of reads or updates. second, , related first, using read on table issues low level table lock. however, in order update occur, must have exclusive table lock, , else (even low level) prevent happening , go lock queue.

there no fixing because design.


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