C++ Qt5 SQLite 操作示例

#pragma once
#include <QSqlDatabase>
#include <QSqlQuery>
#include <QSqlError>
#include <QSqlRecord>
#include <QDebug>
#include <QDir>
#include <iostream>
#include "CGlobal.h"

class MainDB
{
public:
    MainDB(std::string connection);

    /// 插入记录
    bool insertExpressLog(Info info);
    /// 查询是否已录入
    bool checkExpressIfExists(QString eNumber);
private:
    std::string connection_;

    QSqlDatabase db;

    void initDb();
    /// 查询表是否存在
    bool exists(std::string table);
    /// 初始化记录表
    bool initETable();

};

#include "MainDB.h"

MainDB::MainDB(std::string connection):
    connection_(connection)
{
    initDb();
}

void MainDB::initDb()
{
    QString connection = QString::fromStdString(connection_);

    /// 创建连接
    if (QSqlDatabase::contains(connection))
    {
        db = QSqlDatabase::database(connection);
    }else {
        QString DBPath = "Data";
        QDir my_dir(DBPath);
        if (!my_dir.exists())
            my_dir.mkpath(DBPath);

        DBPath += "/" + connection + ".db";

        qDebug() << DBPath.toUtf8() << "##########################";
        /// 第二个参数可以设置连接名字，这里为default
        db = QSqlDatabase::addDatabase("QSQLITE", connection);
        /// 设置数据库名与路径
        db.setDatabaseName(DBPath);
    }

    //打开连接
    if (!db.open())
    {
        qDebug() << db.lastError();
        qFatal("Failed to connect.");
    }
}

bool MainDB::exists(std::string table) {
    try {
        QSqlQuery query(db);
        query.exec(QString::fromStdString(u8"SELECT * FROM " + table));
        return query.next();
    }
    catch (...) {
        return false;
    }
}

bool MainDB::insertELog(eInfo info)
{
    QSqlQuery qry(db);
    qry.prepare(u8"INSERT INTO e_log (e_number,e_label) VALUES (:e_number,:e_label)");
    qry.bindValue(":e_number", QVariant(info.eNumber));
    qry.bindValue(":e_label", QVariant(info.eLabel));
    if (!qry.exec()) {
        qDebug() << qry.lastError();
        return false;
    }
    else {
        return true;
    }
}

bool MainDB::initETable()
{
    QSqlQuery query(db);
    return query.exec(QString::fromStdString(u8"create table e_log(e_number varchar(20) primary key,e_label varchar(20))"));
}

bool MainDB::checkEIfExists(QString eNumber)
{
    if (!exists("e_log"))
    {
        initETable();
    }
    else {

        QVariant en(eNumber);
        QSqlQuery qry(db);
        qry.prepare(u8"SELECT * FROM e_log WHERE e_number=:enumber");
        qry.bindValue(":enumber", en);
        if (!qry.exec())
            qDebug() << qry.lastError();
        else if (qry.next())
        {
            /*QSqlRecord rec = qry.record();

            int cols = rec.count();

            for (int r = 0; qry.next(); r++)
                for (int c = 0; c < cols; c++)
                    qDebug() << QString("Row %1, %2: %3").arg(r).arg(rec.fieldName(c)).arg(qry.value(c).toString());*/

            return true;
        }
    }
    return false;
}