Qt的SQL操作，DELETE，SELECT

#include <QObject>

#include <QSqlDatabase>

#include <QSqlError>

#include <QSqlQuery>

#include <QString>

 

class DatabaseManager : public QObject

    {

    public:

        DatabaseManager(QObject *parent = 0);

        ~DatabaseManager();

 

    public:

        bool openDB();

        bool deletePerson(int id);

 

    private:

        QSqlDatabase db;

    };

Delete a person from the database:

bool DatabaseManager::deletePerson(int id)

    {

    bool ret = false;

    if (db.isOpen())

        {

        QSqlQuery query;

        ret = query.exec(QString("delete from person where id=%1").arg(id));

        }

    return ret;

    }

The rest of the code:

bool DatabaseManager::openDB()

    {

    // Find QSLite driver

    db = QSqlDatabase::addDatabase("QSQLITE");

 

    #ifdef Q_OS_LINUX

    // NOTE: We have to store database file into user home folder in Linux

    QString path(QDir::home().path());

    path.append(QDir::separator()).append("my.db.sqlite");

    path = QDir::toNativeSeparators(path);

    db.setDatabaseName(path);

    #else

    // NOTE: File exists in the application private folder, in Symbian Qt implementation

    db.setDatabaseName("my.db.sqlite");

    #endif

 

    // Open databasee

    return db.open();

    }

以上参考http://developer.nokia.com/community/wiki/Deleting_data_from_a_database_in_Qt

SELECT核心语句

bool DatabaseManager::getPerson(int id, PersonData*& person)

    {

    bool ret = false;

 

    QSqlQuery query(QString("select * from person where id = %1").arg(id));

    if (query.next())

        {

        person->id = query.value(0).toInt();

        person->firstname = query.value(1).toString();

        person->lastname = query.value(2).toString();

        person->age = query.value(3).toInt();

        ret = true;

        }

 

    return ret;

    }

以上参考http://developer.nokia.com/community/wiki/Searching_for_data_in_a_database_in_Qt

 

如果有多个参数，可以是 %1，%2，%3 之后.arg().arg().arg()括号里填对应变量。