JAVA高级面试进阶训练营视频教程

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课题需要做一个数据展示程序， 我就想到了Qt， 连接mysql的过程中是挺简单的， 但是还是有两个坑。。。

               一号坑： Qt 和 mysql 位数要相同！！！ 我的就是不相同， 卸了mysql重装的。

MYSQL的 lib目录，把下面的.lib和.dll结尾的文件全部复制到QT的bin目录下

贴一个建立连接的函数:

bool createConnection()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("hostname");
    db.setPort(3306);
    db.setUserName("root");
    db.setPassword("key");
    db.setDatabaseName("databasename");
    if (!db.open()) {
        QMessageBox::warning(0, QObject::tr("Database Error"),
                             db.lastError().text());
        qDebug() << QSqlDatabase::drivers();
        return false;
    }
    db.exec("SET NAMES 'UTF-8'"); ///设置utf-8编码
    return true;
}

 

一般来讲， 这样就可以了。

               二号坑：中文乱码问题， 主要是Mysql和qt编码不一致导致的。

开始改吧。

mysql> show variables like 'character_set_%';
+--------------------------+----------------------------------------------------+
| Variable_name            | Value                                              |
+--------------------------+----------------------------------------------------+
| character_set_client     | gbk                                                |
| character_set_connection | gbk                                                |
| character_set_database   | utf8mb4                                            |
| character_set_filesystem | binary                                             |
| character_set_results    | gbk                                                |
| character_set_server     | latin1                                             |
| character_set_system     | utf8                                               |
| character_sets_dir       | C:\Program Files (x86)\MySQL\win32\share\charsets\ |
+--------------------------+----------------------------------------------------+
8 rows in set (0.00 sec)

mysql> set character_set_client=utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_connection = utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_database = utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_results = utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_server= utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> set character_set_system = utf8;
ERROR 1238 (HY000): Variable 'character_set_system' is a read only variable
mysql> set collation_server = utf8;
ERROR 1273 (HY000): Unknown collation: 'utf8'
mysql> set collation_server = utf8mb4_unicode_ci;
Query OK, 0 rows affected (0.00 sec)

mysql> set collation_database = utf8mb4_unicode_ci;
Query OK, 0 rows affected (0.00 sec)

mysql> set collation_connection = utf8mb4_unicode_ci;
Query OK, 0 rows affected (0.00 sec)

这就改好了mysql。

qt程序 main()中， 再加一句QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));

然后 ， 就没有然后了。