Bug #67613 ExecuteReader throws NullReferenceException when using variables in queries

• Submitted: 16 Nov 2012 14:54
• Modified: 20 Dec 2012 16:28
• Reporter: Dieter Bernauer-Schilcher
• Status: No Feedback
• Category: Connector / NET
• Severity: S2 (Serious)
• Version: 6.6.4
• OS: Windows
• CPU Architecture: Any

[16 Nov 2012 14:54] Dieter Bernauer-Schilcher

Description:
using query's like this to get rownumbers:
SELECT @rownum:=@rownum+1  as ROWID,ivr.pid  as Project ,SUM(ivr.duration)/60 as Minutes,SUM(ivr.calls) as Calls FROM cdr_dailysum as ivr   left join project p  on ivr.pid=p.pid left join Users u on p.userID=u.ID ,
(SELECT @rownum:=0) r WHERE ((ivr.DATE>='2012-11-01'  AND ivr.DATE<='2012-11-30'  )) GROUP BY ivr.pid  ORDER BY ivr.pid

and passing this query through MysqlCommand.ExecuteReader(CommandBehavior.CloseConnection)  results in:
Fatal error encountered during command execution.
InnerException {"Parameter '@rownum' must be defined."} System.Exception {MySql.Data.MySqlClient.MySqlException}.

Query can be Executed in querybrowser without problems returning proper results

Mysql version is 5.5.28-1.
Behaves like BUG #58652 that is "fixed" since 2010. LOL.

How to repeat:

Do simple query like this:
string query="SELECT @rownum:=@rownum+1  as ROWID, ID from table ,(SELECT @rownum:=0) r";
            MySqlCommand cmd = new MySqlCommand(query);
            cmd.CommandType = CommandType.Text;
            cmd.CommandTimeout = 60;

          
            cmd.Connection = MyConnectionString;

            IDataReader rdr;

            try
            {
                rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch(MySqlException x)
            {
               
               
            }

[20 Nov 2012 16:28] Fernando Gonzalez.Sanchez

Hi, you need to add "Allow User Variables=true" to your connection string
(so the @vars not get interpreted like parameters).

[21 Dec 2012 1:00] Bugs System

No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".