‘QSqlDatabase’ was not declared

Question

I am very new to using QT4. I am trying to use sql in an already working application. However, when I try to compile I get this error: "‘QSqlDatabase’ was not declared in this scope."

Here is the relevent code:

#include <QtSql>
QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");

 db.setHostName("bigblue");
 db.setDatabaseName("flightdb");
 db.setUserName("acarlson");
 db.setPassword("1uTbSbAs");
 bool ok = db.open();

I have added QT += sql to my .pro file.

The code above it literally copied from here:http://qt.nokia.com/doc/4.5/qtsql.html

Any idea what I am doing wrong?

Or if anyone has a decent tutorial on this that would also be helpful. I just cant seem to find good docs — Piratebill
– Piratebill, Commented Nov 15, 2009 at 23:24
If it's not finding QtSql it looks like a problem with your Qt installation — PiedPiper
– PiedPiper, Commented Nov 15, 2009 at 23:35
I have these packages installed: libqt4-core libqt4-debug libqt4-gui libqt4-qt3support libqt4-sql qt4-designer qt4-dev-tools qt4-doc qt4-qtconfig What do you think I am missing? — Piratebill
– Piratebill, Commented Nov 15, 2009 at 23:48
What compiler command line does make produce? Your code compiles ok for me — PiedPiper
– PiedPiper, Commented Nov 15, 2009 at 23:54

Piratebill · Accepted Answer · 2009-11-16 00:23:51Z

5

Ok, the problem was with my .pro file. This is the file that gave me the error:

TEMPLATE = app
QT += sql
QT = gui core
CONFIG += qt debug warn_on console
DESTDIR = bin
OBJECTS_DIR = build
MOC_DIR = build
UI_DIR = build
FORMS = ui/mainwindow.ui ui/dialog.ui ui/dialog_con.ui ui/add_ingredient.ui
HEADERS = src/mainwindowimpl.h \
src/dialogimpl.h \
src/utils.h \
SOURCES = src/mainwindowimpl.cpp \
src/main.cpp \
src/dialogimpl.cpp \
src/utils.cpp \

The problem was that QT=gui core was overriding my QT+=sql. by moving the QT+=sql to bo right above HEADERS, it compiled just fine. Thanks for the help.

answered Nov 16, 2009 at 0:23

Piratebill

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1 Comment

Federico Over a year ago

I think that usually you shouldn't assign (with = )variables on a qmake file, but is better to add or remove values from them (with += or -=), or you can have some side effects as it happened to you.

sth · Accepted Answer · 2009-11-15 23:56:15Z

2

The compiler can't find the QtSql header and therefore doesn't know about QSqlDatabase. The header is in the QtSql subdirectory, so maybe you need to explicitly specify this in the include line:

#include <QtSql/QtSql>

Alternatively you have to make sure that the QtSql directory is in the include file search path of your compiler.

answered Nov 15, 2009 at 23:56

sth

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2 Comments

Piratebill Over a year ago

That just made it go from 3 errors, to 10. Do you want me to post them all?

sth Over a year ago

Usually the first error is the most significant one... What does the first error message say?

Dirk is no longer here · Accepted Answer · 2009-11-15 23:25:24Z

-1

I think you just need a

#include <QSqlDatabase>

as this is not automatically included by QtSql.

answered Nov 15, 2009 at 23:25

Dirk is no longer here

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3 Comments

Piratebill Over a year ago

Just tried it, here are the new errors. error: QtSql: No such file or directory src/mainwindowimpl.cpp:9:24: error: QSqlDatabase: No such file or directory src/mainwindowimpl.cpp: In member function ‘void MainWindowImpl::not_done()’: src/mainwindowimpl.cpp:58: error: ‘QSqlDatabase’ was not declared in this scope src/mainwindowimpl.cpp:58: error: expected `;' before ‘db’ src/mainwindowimpl.cpp:59: error: ‘db’ was not declared in this scope src/mainwindowimpl.cpp:63: warning: unused variable ‘ok’

MatBailie Over a year ago

"I'm right, you're wrong" doesn't tend to make be trust you any more than the other person. Any supporting evidence for your statement?

PiedPiper Over a year ago

@Dems /usr/include/qt4/QtSql/QtSql contains the line: #include "qsqldatabase.h" Is that enough evidence?

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