QT 创建本地数据库(SQLite数据库)存储数据

Posted 2020-11-24 远方是什么样子

 

注意：QT自带SQLITE数据库,不需要再安装

 

1.创建一个包含创建、查询、修改和删除数据库的数据库类(DataBase)

DataBase.h头文件

#pragma once

#include <QObject>
#include <QtSql/QSqlDatabase>
#include <QtSql/QSqlQuery>
#include <QtSql/QSqlDriver>
#include <QtSql/QSqlError>
#include "client_global.h"

struct StudentData
{
　　QString name;
　　int score;
　　QString grade;
};

class DataBase : public QObject
{
    Q_OBJECT

public:
    DataBase(QString name,QObject *parent=0);
    ~DataBase();

public:
    bool insertData(StudentData data);
    bool deleteData(int name);
    bool getDataByName(int name, StudentData & data);
    bool getDataList(QList<StudentData> & list);
　　 bool update();
private:
    QSqlDatabase m_DataBase;
private:
    bool initTable();
    bool isExistTable(QString table);
    bool createTable(QString table);
};

 

DataBase.cpp源文件

#include "XDataBase.h"
#include <QCoreApplication>
#include <QDebug>
#include <QSqlRecord>


DataBase::DataBase(QString name, QObject *parent)
    : QObject(parent)
{
    
    if (QSqlDatabase::contains(name)) {

        m_DataBase = QSqlDatabase::database(name);
    }
    else {

        m_DataBase = QSqlDatabase::addDatabase("QSQLITE");
        m_DataBase.setDatabaseName(name+".db");
        m_DataBase.setDatabaseName(QCoreApplication::applicationDirPath()+"//"+ name);
    }
    initTable();
}

DataBase::~DataBase()
{
}

bool DataBase::initTable()
{
    if (!m_DataBase.open()) {
        return false;
    }

    if (!isExistTable("students")) {
        createTable("students");
    }
    return false;
}

bool DataBase::isExistTable(QString table)
{
    bool bRet = false;
    if (!m_DataBase.open()) {
        return bRet;
    }
    QSqlQuery query(m_DataBase);
    query.exec(QString("select count(*) from sqlite_master where type=‘table‘ and name=‘%1‘").arg(table));    //关键的判断      
    if (query.next())
    {
        if (query.value(0).toInt() > 0)
        {
            bRet = true;
        }
    }
    return false;
}

bool DataBase::createTable(QString table)
{
    if (!m_DataBase.open()) {
        return false;
    }

    QSqlQuery query(m_DataBase);
    if (table == QString("students")) {

        bool success = query.exec("CREATE TABLE students ("
                                    "id INTEGER PRIMARY KEY AUTOINCREMENT, "
                                    "name VARCHAR(40) NOT NULL, "
                                    "score INTEGER NOT NULL, "
                                    "grade VARCHAR(40) NOT NULL)");

        if (success) {
            return true;   //新建数据库成功
        }
        else {
            QSqlError lastError = query.lastError();
            QString err = lastError.driverText();
            return false;
        }
    }
    else {
        return false;
    }
}

bool DataBase::insertData(StudentData data)
{
    if (!m_DataBase.open()) {
        return false;
    }
    QSqlQuery query(m_DataBase);

    bool success = query.exec(QString("INSERT INTO students (name, score,class) "
        "VALUES (%1, %2, %3)").arg(data.name)
                              .arg(data.score)
                              .arg(data.grade));
        
    if (!success) {

        QSqlError lastError = query.lastError();
        QString err = lastError.driverText();
        return false;
    }
    return true;
}

bool DataBase::deleteData(QString name)
{
    if (!m_DataBase.open()) {
        return false;
    }
    QSqlQuery query(m_DataBase);
    query.prepare(QString("DELETE FROM students WHERE name=‘%1‘").arg(name));
    query.exec();
    return false;
}

bool DataBase::getDataByName(int name, StudentData & data)
{
    if (!m_DataBase.open()) {
        return false;
    }

    QSqlQuery query(m_DataBase);
    query.prepare(QString("SELECT * FROM students WHERE name=‘%1‘").arg(name));
    query.exec();
    QSqlRecord rec = query.record();
    if (query.next())
    {
        
        data.name = query.value(0).toString();
        data.score = query.value(1).toInt();
        data.grade = query.value(2).toString();
        
        return true;
    }
    return false;
}

bool DataBase::getDataList(QList<StudentData>& list)
{
    if (!m_DataBase.open()) {
        return false;
    }

    QSqlQuery query(m_DataBase);
    query.prepare(QString("SELECT * FROM students"));
    query.exec();
    QSqlRecord rec = query.record();
    while (query.next())
    {
        StudentData data;
        device.name = query.value(0).toInt();
        device.score = query.value(1).toString();
        device.grade = query.value(2).toInt();
        list.append(data); 
        return true;
    }
    return false;
}

bool DataBase::update()
{
    if (!m_DataBase.open()) {
        return false;
    }

    QSqlQuery query(m_DataBase);
    query.prepare("UPDATE students SET score = 100 , name = ‘小A‘");
    query.exec();
    return false;
}

 

 

 

调用：

XClientApp.h头文件

#pragma once

#include <QApplication>
#include <DataBase.h>
#include "ServerAPI.h"
#define clientApp static_cast<XClientApp*>(QCoreApplication::instance())

class XClientApp : public QApplication
{
    Q_OBJECT

public:
    XClientApp(int argc, char *argv[]);
    ~XClientApp();
    DataBase* getDataBase();
    ServerAPI* getServerAPI();
    QString getAppName();
private:
    void setFont(QString font);
    void setStyle();
private:
    DataBase* m_pDataBase;
    ServerAPI* m_pServerAPI;
signals:
    void sglSystemMessage(QString type, QString data);
};

 

 

XClientApp.cpp源文件

 

#include "XClientApp.h"

XClientApp::XClientApp(int argc, char *argv[])
    : QApplication(argc, argv)
{
    
     m_pDataBase = new DataBase("xclient", this);
     setWindowIcon(QIcon(":/Images/Resources/朱砂古镇.ico"));//可执行程序图标
     setStyle();
     m_pServerAPI = new ServerAPI(this);   //注意有重载
}

DataBase * XClientApp::getDataBase()   //获取本地数据库并进行操作
{
    return m_pDataBase;
}