Qt中使用QSqlDatabase sqlite3

#ifndef DBUTIL_H
#define DBUTIL_H

#include 
#include 



/**
 * database util
 */
class DBUtil
{

public:
    DBUtil();
    ~DBUtil();


public:
    void close();

    bool insert_data(
            const QString& sql_str);

    void update_data(
            const QString& sql_str);

    QMap select_line_data(
            const QString& sql_str);

    // select many row data
    QVector >
    select_data(
            const QString& sql_str);

    bool select_exist(
            const QString& sql_str);

    void delete_data(
            const QString& sql_str);


private:
    bool connect();


private:
    QString get_database_name();



private:
    QSqlDatabase d_db;




};

#endif // DBUTIL_H 

#include "DBUtil.h"
#include "DBConstant.h"
#include "GLOBAL/util/CommonFileUtil.h"

#include 
#include 
#include 
#include 




DBUtil::DBUtil()
{
}



DBUtil::~DBUtil()
{}



void
DBUtil::close()
{

}



QString
DBUtil::get_database_name()
{
    return CommonFileUtil::get_db_dir() + "/" + DBConstant::c_SQLITE3_DATABASE_NAME;
}



bool
DBUtil::connect()
{
    d_db = QSqlDatabase::database();
    d_db.setDatabaseName(get_database_name());

    if( !d_db.open() )
    {
        qDebug() << __FILE__ << __LINE__ << "warning: database not connect. " << d_db.lastError() << "\n";
        return false;
    }

    return true;
}



bool
DBUtil::insert_data(
        const QString& sql_str)
{
    const bool& c_ok = connect();
    if( !c_ok )
    {
        return false;
    }

    QSqlQuery q;
    bool ok = q.exec(sql_str);
    if( !ok )
    {
        qDebug() << __FILE__ << __LINE__ << " error: " << q.lastError() << "\n";
    }

    q.clear();
    d_db.close();

    return ok;
}



void
DBUtil::update_data(
        const QString& sql_str)
{
    const bool& c_ok = connect();
    if( !c_ok )
    {
        return;
    }

    QSqlQuery q;
    q.exec(sql_str);

    q.clear();
    d_db.close();
}



QMap
DBUtil::select_line_data(
        const QString& sql_str)
{
    QMap map_result_data;
    const bool& c_ok = connect();
    if( !c_ok )
    {
        return map_result_data;
    }

    QSqlQuery q;
    if( !q.exec(sql_str) )
    {
        d_db.close();
        return map_result_data;
    }

    if( q.next() )
    {
        for(int i = 0; i < q.record().count(); i++)
        {
            //qDebug() << __FILE__ << __LINE__ << " i = " << i;
            map_result_data[q.record().fieldName(i)] = q.value(i).toString();
        }
    }

    q.clear();
    d_db.close();

    //qDebug() << __FILE__ << __LINE__ << " map_result_data = " << map_result_data;

    return map_result_data;
}



QVector >
DBUtil::select_data(
        const QString& sql_str)
{
    QVector > result_data;
    const bool& c_ok = connect();
    if( !c_ok )
    {
        return result_data;
    }

    QSqlQuery q;
    if( !q.exec(sql_str) )
    {
        d_db.close();
        return result_data;
    }

    QMap column_data;

    while( q.next() )
    {
        for(int i = 0; i < q.record().count(); i++)
        {
            column_data[q.record().fieldName(i)] = q.value(i).toString();
        }

        result_data.push_back(column_data);
    }

    //qDebug() << __FILE__ << __LINE__ << "select_data result_data = " << result_data;

    q.clear();
    d_db.close();
    return result_data;
}



bool
DBUtil::select_exist(
        const QString& sql_str)
{
//    const QVector >& data = select_data(sql_str);
//    return (!data.empty());

    const bool& c_ok = connect();
    if( !c_ok )
    {
        qDebug() << __FILE__ << __LINE__ << "warning: database not connect.";
        return false;
    }

    QSqlQuery q;
    if( !q.exec(sql_str) )
    {
        d_db.close();
        return false;
    }

    if( q.next() && (q.record().count() > 0) )
    {
         return true;
    }

    return false;
}



void
DBUtil::delete_data(
        const QString& sql_str)
{
    const bool& c_ok = connect();
    if( !c_ok )
    {
        return;
    }

    QSqlQuery q;
    q.exec(sql_str);

    d_db.close();
} 

一时之间，发现写了很多小练习的代码^_