Windows下实现Qt与MySQL连接

本文记录了在Windows下实现Qt与MySQL连接的步骤。

QtSDK并未提供MySQL的驱动链接库，但是在Qt的开源源码中有MySQL驱动的代码，先将其编译才能正确地连接数据库，网上提到的编译步骤都是先写好.pro文件再用命令行方式编译，但是新版的Qt没有提供命令行，我是通过QtCreator直接编译成功的，而且.pro文件已经由官方提供了。

※ Qt的MySql驱动的编译过程如下

①F:\open-source projects\qt-qt-4.8\qt-qt\src\plugins\sqldrivers\mysql在qt源码目录下找到qt的mysql驱动源码，官方已提供.pro文件，导入到QtCreator中去

②将mysql自带的libmysql.lib文件放到C:\QtSDK\Desktop\Qt\4.7.4\mingw\lib下

③将mysql自带的include文件夹放到C:\QtSDK\Desktop\Qt\4.7.4\mingw\include\QtSql下

④在QtCreator中编译mysql驱动，直接点击编译按钮，即可完成编译，不需要命令行

⑤将编译得到的所有文件拷贝到C:\QtSDK\Desktop\Qt\4.7.4\mingw\plugins\sqldrivers下

⑥将mysql自带的libmysql.dll文件拷贝到连接MySQL的程序的release文件夹下面，即可运行这种连接mysql的程序

※ 运用Qt的QSqlDatabase等类库，可以用和JDBC几乎相同的方式连接到MySQL。这一过程十分简单。Qt还提供了和数据库相关联的一些GUI类，使用起来十分方便。下面给出一个具体的例子。其他的数据库操作，可以看qt文档，上面写的非常详细。

#ifndef CONNECTION_H
#define CONNECTION_H

#include <QMessageBox>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>

static bool createConnection()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("world");
    db.setUserName("root");
    db.setPassword("1234");
    if (!db.open()) {
        QMessageBox::critical(0, qApp->tr("Cannot open database"),
            qApp->tr("Unable to establish a database connection.\n"
                     "This example needs SQLite 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;
}


明天研究Qt的DataStream究竟能否实现序列化