Reusing a QsqlQuery object too many times causes an unhandled exception SOLVED
-
I have a very simple Qt based application (4.6.3) running on a Window7 system that is connecting to an MSSQL database running on a separate server. I can successfully make a connection to the DB and perform queries successfully.
However, if i attempt to reuse the same QSqlQuery object a number of time, the query.exec() generates an Unhandled exception. In the code snippet below, the 3rd query fails. I have simplified the code sample for this post. I have tried to do a query.finish() after each query has been processed with no success. I then tried to use query.clear(), but that would also ALWAYS throw an unhandled exception. no matter when it is executed.
The code was built and tested via Visual Studio.If I use a new QSqlQuery option for each query, the queries succeed.
Am I doing something incorrectly?
Thank You,Arnie
@
int main( int argc, char *argv[])
{
QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
db.setHostName("myhostname");
db.setDatabaseName("mydsn");
db.setUserName("myuserid");
db.setPassword("mypassword");
bool ok = db.open();
QSqlQuery query;query.exec("Select id from myTable");
while (query.next())
{
int id = query.value(0).toInt();
qDebug() << id;
}query.exec("Select id from myTable");
while (query.next())
{
int id = query.value(0).toInt();
qDebug() << id;
}query.exec("Select id from myTable"); //<--THIS query.exec never gets executed. The exception happens
//here
while (query.next())
{
int id = query.value(0).toInt();
qDebug() << id;
}
......
@ -
My previous post should have said that the query.clear() ALWAYS throws an exception whenever it is executed. Sorry about that mistake.
-
I have solved this problem. It turns out that while I was linking in the wrong versions of the Qt dlls. I was in some cases linking in the the debug version in the release build or the release version in the debug build. Once I figured this all of the unhandled exceptions were resolved.