While fetching data from a union query as shown in the code fragment
below I get the following error when fetching the data from the second
part which is only one row. The same behaviour is found when using a
similar query also limited to one row:
Untreated Exception at 0x102163d4 (msvcr71d.dll) in analysis.exe:
0xC0000005: AccessError-Writeposition 0x20333535.

The data access crashes when I either want to assign a row to the SSQL
struct dbEvent or when accessing to the data with row["name"] .

Is there another option to access the data?

Etienne

//set up query
sprintf(queryString, "(Select * from event where Measurements_ID =
'%.4d-%.2d-%.2d %.2d:%.2d:%.2d' and Event_DataFilePos >= %d and
Event_DataFilePos <= %d order by Event_DataFilePos)",
m_startYear, m_startMonth, m_startDay, m_startHour,
m_startMinute, m_startSecond, dataFileFirstPosition, dataFileLastPosition);
sprintf(queryString,"%s UNION DISTINCT (Select * from event
where Measurements_ID = '%.4d-%.2d-%.2d %.2d:%.2d:%.2d' and
Event_DataFilePos >= %d and Event_Type = 'p' order by Event_DataFilePos
ASC LIMIT 1)",
queryString, m_startYear, m_startMonth, m_startDay,
m_startHour, m_startMinute, m_startSecond, dataFileLastPosition,
dataFileLastPosition);

resUse = query.use(queryString);

//Access data from query
while (row = resUse.fetch_row())
{
dbEvent = row;
//event[counter].dataFilePosition = row["Event_DataFilePos"];



--
++++++++++++++++++++++++++++++++++++++++++++++
Dr. Etienne Hirt Art of Technology
Director R&D www.art-of-technology.ch
Technoparkstrasse 1 Ph: +41-43-311 77 02
8005 Zurich Sw: +41-43-311 77 00
Switzerland
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Etienne Hirt wrote:
Some of the examples use this same mechanism, so I'd be surprised if the
bug is truly in MySQL++.

Were you have to use an earlier version successfully?

Have you tried running the examples?

It says you aren't catching an exception: is this code wrapped in a try
block?

What is the type of this dbEvent data structure?

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Dear Warren,

Thanks for the questions. Please find some answers and questions below

Warren Young wrote:

I found no union query. Do you mean multiple queries?

I did not use an earlier version

Which one do your recommend for testing? Is it the multiple query?

yes but only mysql specific

Its an SSQL:
sql_create_11 (Event, 2, 11, string, Measurements_ID, int32,
Event_DataFilePos,
mysqlpp::sql_char, Event_Type, int32, Event_Lat, int32,
Event_Lon,
int16, Event_Height, int16, Event_Speed, int16,
Event_Direction,
int16, Event_Accuracy, uint16, Event_Fix, string,
Event_Comment)





--
++++++++++++++++++++++++++++++++++++++++++++++
Dr. Etienne Hirt Art of Technology
Director R&D www.art-of-technology.ch
Technoparkstrasse 1 Ph: +41-43-311 77 02
8005 Zurich Sw: +41-43-311 77 00
Switzerland
==============================================


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Etienne Hirt wrote:
No, I simply mean the model of calling use() to get a result set and
then accessing the data with operator[](const char*).

Run all of simple* and custom* at least. If any of them fail, that
could be a useful clue.

Ah, that could be the problem. Try accessing the data fields directly,
instead of assigning it to an SSQLS. It may be that SSQLS isn't
flexible enough to deal with a result set coming from multiple tables.

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