‘QSqlDatabase’ was not declared

Question

Hi, 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?

Answer 1

I think you just need a

#include <QSqlDatabase>

as this is not automatically included by QtSql.

Answer 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.

Answer 3

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.