这是什么错误，大家帮帮忙，谢了！

[xonorya]

我从Qt的例子文件夹下拷贝了一个文件夹，想自己试试数据库的编译，make时总是说我的：

QtSql:没有该文件或目录！（这个类似提示，好像在我编译的时候很常见）

大家帮忙看看怎么回事阿？谢谢了！
附：我在.pro文件中也加了：Qt ＋＝sql，有时候自己被改回来了，怎么回事？
以下是我源代码：
不想拷贝的下载我的压缩包（两份一样的，只是格式不同！）吧，我真的需要你们的帮助，再拜谢！！！！
//======================connection.h=========================
#ifndef CONNECTION_H
#define CONNECTION_H

#include <QMessageBox>
#include <QtSql>
#include <QSqlError>
#include <QSqlQuery>
//<QSqlDatabase>
static bool createConnection()
{
QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
db.setDatabaseName("memory");
db.setHostName("123cn");
db.setUserName("nobody");
db.setPassword("xooo");
if (!db.open()) {
QMessageBox::critical(0, qApp->tr("Cannot open database"),
qApp->tr("Unable to establish a database connection.\n"
"This example needs MYSQL support. Please read "
"the Qt SQL driver documentation for information how "
"to build it.\n\n"
"Click Cancel to exit."), QMessageBox::Cancel);
return false;
}

QSqlQuery query;
query.exec("create table person (id int primary key, "
"firstname varchar(20), lastname varchar(20))");
query.exec("insert into person values(101, 'Danny', 'Young')");
query.exec("insert into person values(102, 'Christine', 'Holand')");
query.exec("insert into person values(103, 'Lars', 'Gordon')");
query.exec("insert into person values(104, 'Roberto', 'Robitaille')");
query.exec("insert into person values(105, 'Maria', 'Papadopoulos')");

query.exec("create table offices (id int primary key,"
"imagefile int,"
"location varchar(20),"
"country varchar(20),"
"description varchar(100))");
query.exec("insert into offices "
"values(0, 0, 'Oslo', 'Norway',"
"'Oslo is home to more than 500 000 citizens and has a "
"lot to offer.It has been called \"The city with the big "
"heart\" and this is a nickname we are happy to live up to.')");
query.exec("insert into offices "
"values(1, 1, 'Brisbane', 'Australia',"
"'Brisbane is the capital of Queensland, the Sunshine State, "
"where it is beautiful one day, perfect the next. "
"Brisbane is Australia''s 3rd largest city, being home "
"to almost 2 million people.')");
query.exec("insert into offices "
"values(2, 2, 'Redwood City', 'US',"
"'You find Redwood City in the heart of the Bay Area "
"just north of Silicon Valley. The largest nearby city is "
"San Jose which is the third largest city in California "
"and the 10th largest in the US.')");
query.exec("insert into offices "
"values(3, 3, 'Berlin', 'Germany',"
"'Berlin, the capital of Germany is dynamic, cosmopolitan "
"and creative, allowing for every kind of lifestyle. "
"East meets West in the metropolis at the heart of a "
"changing Europe.')");
query.exec("insert into offices "
"values(4, 4, 'Munich', 'Germany',"
"'Several technology companies are represented in Munich, "
"and the city is often called the \"Bavarian Silicon Valley\". "
"The exciting city is also filled with culture, "
"art and music. ')");
query.exec("insert into offices "
"values(5, 5, 'Beijing', 'China',"
"'Beijing as a capital city has more than 3000 years of "
"history. Today the city counts 12 million citizens, and "
"is the political, economic and cultural centre of China.')");

query.exec("create table images (locationid int, file varchar(20))");
query.exec("insert into images values(0, 'images/oslo.png')");
query.exec("insert into images values(1, 'images/brisbane.png')");
query.exec("insert into images values(2, 'images/redwood.png')");
query.exec("insert into images values(3, 'images/berlin.png')");
query.exec("insert into images values(4, 'images/munich.png')");
query.exec("insert into images values(5, 'images/beijing.png')");



return true;
}
//! [0]

#endif

//===========================main.cpp=================
#include <QApplication>

#include "connection.h"
#include "tableeditor.h"

//! [0]
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
if (!createConnection())
return 1;

TableEditor editor("person");
editor.show();
return editor.exec();
}
//! [0]

//==========================tableeditor.cpp===============
#include <QtGui>
#include <QtSql>

#include "tableeditor.h"

//! [0]
TableEditor::TableEditor(const QString &tableName, QWidget *parent)
: QDialog(parent)
{
model = new QSqlTableModel(this);
model->setTable(tableName);
model->setEditStrategy(QSqlTableModel::OnManualSubmit);
model->select();

model->setHeaderData(0, Qt::Horizontal, tr("ID"));
model->setHeaderData(1, Qt::Horizontal, tr("First name"));
model->setHeaderData(2, Qt::Horizontal, tr("Last name"));

//! [0] //! [1]
QTableView *view = new QTableView;
view->setModel(model);
//! [1]

//! [2]
submitButton = new QPushButton(tr("Submit"));
submitButton->setDefault(true);
revertButton = new QPushButton(tr("&Revert"));
quitButton = new QPushButton(tr("Quit"));

buttonBox = new QDialogButtonBox(Qt::Vertical);
buttonBox->addButton(submitButton, QDialogButtonBox::ActionRole);
buttonBox->addButton(revertButton, QDialogButtonBox::ActionRole);
buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);
//! [2]

//! [3]
connect(submitButton, SIGNAL(clicked()), this, SLOT(submit()));
connect(revertButton, SIGNAL(clicked()), model, SLOT(revertAll()));
connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
//! [3]

//! [4]
QHBoxLayout *mainLayout = new QHBoxLayout;
mainLayout->addWidget(view);
mainLayout->addWidget(buttonBox);
setLayout(mainLayout);

setWindowTitle(tr("Cached Table"));
}
//! [4]

//! [5]
void TableEditor::submit()
{
model->database().transaction();
if (model->submitAll()) {
model->database().commit();
} else {
model->database().rollback();
QMessageBox::warning(this, tr("Cached Table"),
tr("The database reported an error: %1")
.arg(model->lastError().text()));
}
}
//! [5]

//=====================tableeditor.h====================
#ifndef TABLEEDITOR_H
#define TABLEEDITOR_H

#include <QDialog>

QT_BEGIN_NAMESPACE
class QDialogButtonBox;
class QPushButton;
class QSqlTableModel;
QT_END_NAMESPACE

//! [0]
class TableEditor : public QDialog
{
Q_OBJECT

public:
TableEditor(const QString &tableName, QWidget *parent = 0);

private slots:
void submit();

private:
QPushButton *submitButton;
QPushButton *revertButton;
QPushButton *quitButton;
QDialogButtonBox *buttonBox;
QSqlTableModel *model;
};
//! [0]

#endif
//===========================end code======================

[weitaotao110]

你的Qt +=Sql 中，“t“要大写！