qt6 自带pg数据库驱动：

pro文件加个说明：

 

引用位置添加（按需添加，这里我就大致加一下）：

 test code: 理想情况当然是要用pool,这里只是演示调用而已

QSqlError DbTool::testConnection(const QString &driver, const QString &dbName, const QString &host, const QString &user, const QString &passwd, int port)
{// 为每个连接创建一个唯一的标识符static int cCount = 0;// 存储数据库连接的错误信息QSqlError err;// 添加数据库连接并设置连接参数db = QSqlDatabase::addDatabase(driver, QString("myChat%1").arg(++cCount));db.setDatabaseName(dbName);db.setHostName(host);db.setPort(port);// 尝试打开数据库连接if (!db.open(user, passwd)) {// 如果打开失败，获取错误信息并移除数据库连接err = db.lastError();db = QSqlDatabase();QSqlDatabase::removeDatabase(QString("mychat%1").arg(cCount));}else{// QMessageBox::information(0, QObject::tr("Database Information"),//     "Database is connected successfully");qDebug() << "Database is connected successfully";//query table sys_doctorsQSqlQuery query(db);bool b=query.exec("SELECT user_name FROM sys_doctors");if (b){qDebug() << "query success";}else{qDebug() << "query failed";}while (query.next()){QString name = query.value(0).toString();qDebug() << name;}db.close();  }// 返回数据库连接的错误信息（如果有）return err;
}

调用代码：

    QSqlError err = dbtool->testConnection("QPSQL", "myChat", "localhost", "postgres", "1", 5432);if (err.type() != QSqlError::NoError){qDebug() << err.text();}else{qDebug() << "Database is connected successfully";}