在线求解啊啊“QSqlDatabase was not declared in this scope” [复制链接]

具体代码：
#ifndef CONNECTION_H
#define CONNECTION_H
#include <QtSql>
#include <QMessageBox>
#endif // CONNECTION_H



static bool createConnection()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QOLEDB");
    db.setHostName("user-54b1fd6c1e");    
    db.setDatabaseName("housext");
    db.setUserName("sa");
    db.setPassword("sa");
    if (!db.open())
    {
        QMessageBox::information(0,QObject::tr("database"),db.lastError().text());
        return false;
    }
    return true;
}
#endif

//我用的是sql server 2005 里创建了个数据库 名为housext
编译后出现QSqlDatabase was not declared in this scope错误
我是工程里新建了个头文件名为connection.h