PostgreSQL and Trying to connect using Qt

[aftertaf]

...
just build libpq.a from sources . . . .
http://pgolub.wordpress.com/2008/12/15/building-postgresql-client-library-using-mingw-under-winxp-sp3/

don't know what to do with it.
sorry for by n00bness, people...

[clochydd]

It is not necessary to compile postgresql, I used the binaries 32-bit and with installing ./lib and ./include had been provided, too.
Your make does not recognise the psql includes (the stuff, that follows -I) and that's why you still receive the message 'libpq-fe.h not found'.
Do you see the same error if you use backslashed paths with you qmake command? Qt uses forward slashes but I had success with the backslashed command.

[SGaist]

Just to be sure, wouldn't by any chance libpq-fe.h be in include/libpq ? If so it's that last element that was missing.

[clochydd]

Yes, this has been installed in "C:\Program Files (x86)\PostgreSQL\9.3\include" together with the binaries of PostgeSQL 32-bit:
"03.12.2013 06:13 21.082 libpq-fe.h"
and - the PostgreSQl include has to be added to qmake!

[SGaist]

Indeed, but you need to give the full path to libqp-fe.h not just the path that contains the libpq folder.

Please avoid having spaces in your path when developing, it something that is not working very well on windows

[aftertaf]

on my system i installed postgreSQL x86 9.3 to c:\psql93_x86\

so... the qmake command where i specify the INCLUDE+=, LIBS+= etc . . .
i need to tell it precisely and exactly where libqp-fe.h is, including full path ?

how do I do that, i.e. what separator do i use to add more than one entry into the "INCLUDE+=" that i've already specified (using clochydd's tuto on page 2. .) ?

[clochydd]

Go to the Qt plugin source directory:
cd QT_SRC_PATH\src\plugins\sqldrivers\psql

Start building the plugins:
(Change this to your mingw32 path: C:\Qt\Qt5.2.0\5.2.0\mingw48_32\bin)
C:\Qt\Qt5.2.0\5.2.0\mingw48_32\bin\qmake “INCLUDEPATH+=c:\psql93_x86\include”
“LIBS+=c:\psql93_x86\lib\libpq.lib” psql.pro

[SGaist]

libpq-fe.h being in include/libpq

You should use

@“INCLUDEPATH+=c:/psql93_x86/include/libpq”@

[aftertaf]

same :(

[clochydd]

Don't give up - we will find a solution, hopefully!

• Is the qmake error message concerning the libpq-fe.h exactly as before?
• Could you please post the message again?
• Could you post the directory list of c:\psql93_x86\include?

[aftertaf]

just tried making the odbc driver again...
and get the Driver not Loaded message :)

---

C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>c:\Qt\5.2.1\mingw48_32\bin\qm
ake.exe "INCLUDEPATH+=c:/psql93_x86/include/libpq" "LIBS+=c:/psql93_x86/lib/libp
q.lib" psql.pro

C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>mingw32-make debug
mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory 'C:/QT/5.2.1/Src/qtbase/src/plugins/sqldrive
rs/psql'
g++ -c -pipe -fno-keep-inline-dllexport -g -std=c++0x -fno-exceptions -frtti -Wa
ll -Wextra -DUNICODE -DQT_NO_CAST_TO_ASCII -DQT_NO_CAST_FROM_ASCII -DQT_NO_EXCEP
TIONS -DQT_PLUGIN -DQT_SQL_LIB -DQT_CORE_LIB -I. -I"C:\Qt\5.2.1\mingw48_32\inclu
de\QtSql\5.2.1" -I"C:\Qt\5.2.1\mingw48_32\include\QtSql\5.2.1\QtSql" -I"C:\Qt\5.
2.1\mingw48_32\include" -I"C:\Qt\5.2.1\mingw48_32\include\QtSql" -I"C:\Qt\5.2.1
mingw48_32\include\QtCore\5.2.1" -I"C:\Qt\5.2.1\mingw48_32\include\QtCore\5.2.1
QtCore" -I"C:\Qt\5.2.1\mingw48_32\include\QtCore" -I".moc\debug" -I"........
mkspecs\win32-g++" -o .obj\debug\qsql_psql.o ......\sql\drivers\psql\qsql_psql
.cpp
......\sql\drivers\psql\qsql_psql.cpp:59:22: fatal error: libpq-fe.h: No such
file or directory
#include <libpq-fe.h>
^
compilation terminated.
Makefile.Debug:497: recipe for target '.obj/debug/qsql_psql.o' failed
mingw32-make[1]: *** [.obj/debug/qsql_psql.o] Error 1
mingw32-make[1]: Leaving directory 'C:/QT/5.2.1/Src/qtbase/src/plugins/sqldriver
s/psql'
makefile:48: recipe for target 'debug' failed
mingw32-make: *** [debug] Error 2

[aftertaf]

http://pastebin.com/4cpqVMiN
folder contents

[clochydd]

Thanks for the data! I can see our "fatal" libpq-fe.h in c:\psql93_x86\include. So as a first step I suppose to test with:
C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>c:\Qt\5.2.1\mingw48_32\bin\qmake.exe “INCLUDEPATH+=c:\psql93_x86\include” “LIBS+=c:\psql93_x86\lib\libpq.lib” psql.pro
I know, the backslashes are a bit unusual for Qt but it worked with my installs so give it a try! Good luck!

[aftertaf]

i've tried on many occasions with \ and /: same result.

The problem is obviously over my level of unkludging, and I've figured out how to use ODBC instead.

@
#include <QtSql>
#include <QString>
#include <QSqlDatabase>

void connect_db()
{

QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
QStringList driversList = QSqlDatabase::drivers();
qDebug() << "drivers list= " << driversList;
bool bOpen(false);
db.addDatabase("QODBC","odbcname");
db.setHostName("localhost");
db.setDatabaseName("dbname_in_postgres");
db.setUserName("username");
db.setPassword("password");
bOpen =db.open();
QString str=db.lastError().text();
}@

str remains empty :)
and bOpen shows True for the first time in a month's trying.
I dont need pure pg connection, using an ODBC is fine for me at this stage.
Now for trying to make my DAO classes :)
thanks to all for helping, sorry it didn't work out as intended, but for ODBC connections, my above code works.

[Duncan]

Hello!

What did you put for this line:

db.addDatabase("QODBC","odbcname");

Not sure what to put instead of odbcname.

Thanks!

[clochydd]

Hello Duncan,

if you only open one database, you do not need to specify the connection name:

db.addDatabase("QODBC");

If you plan work with more connections, use a name to identify each connection:

db.addDatabase("QODBC","myConn1");

[SGaist]

Hi,

addDatabase is a static function that returns a QSqlDatabase instance that will use the selected backend.

So you must call it like that:
QSqlDatabase db = QSqlDatabase::addDatabase("QODBC")

The suggestion of @clochydd about the connection name still applies.