qt实现sqlite3的级联删除

1.需求

有两张表，条码表和产品详情表，条码表中的rfid为产品表中的rfid外键，要求删除产品表中的相关条目时能实现条码表的级联删除

2.解决

使用qt中的sqlite3自带的级联删除解决这个需求

3.代码

mymain.cpp

#include "mysql.h"
#include <QtWidgets/QApplication>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>
#include <QtCore/QDir>
#include <QMessageBox>

bool createdb();

int main(int argc,char *argv[])
{
    QApplication a(argc,argv);
    createdb();

    mysql w;
    w.show();
    return a.exec();
}

bool createdb()
{
    bool bret = false;
    //这里创建一个db目录存储数据库文件
    QString strdbpath("");
    strdbpath = QCoreApplication::applicationDirPath();
    strdbpath += "/db";
    QDir dir("");
    dir.mkpath(strdbpath);
    strdbpath += "/mysqlite.db";
    QSqlDatabase dbset = QSqlDatabase::addDatabase("QSQLITE","file");
    dbset.setDatabaseName(strdbpath);
    if (!dbset.open()) {
        //LOG_ALL_ERROR(QStringLiteral("failed open mysqlite.db"));
        return bret;
    }

     QSqlQuery setquery(QSqlDatabase::database("file",true));
     if(!setquery.exec("PRAGMA foreign_keys = ON;"))
     {
         QSqlError sqlerror = setquery.lastError();
         QString texterr = sqlerror.text();
         QMessageBox::information(nullptr,"errormsg",texterr);
         return false;
     }

    //商品详情表
    bret = setquery.exec("create table tb_goods(rfid varchar(33) primary key,name varchar(200) not null)");
    if (!bret)
    {
        QSqlError sqlerror = setquery.lastError();
        QString texterr = sqlerror.text();
        if (texterr.contains("already exists",Qt::CaseInsensitive))
            bret = true;
        else
        {
            //LOG_ALL_ERROR(QStringLiteral("failed create table tb_goods."));
            return bret;
        }
    }

    //这里条码对照表和skuid对照表因为可能牵涉到多对多的情况 故没有作为主键
    //条码对照表
    bret = setquery.exec("create table tb_barcode(id INTEGER PRIMARY KEY AUTOINCREMENT,"
                         "barcode varchar(100) not null,rfid varchar(33) not null,"
                         "FOREIGN KEY(rfid) REFERENCES tb_goods(rfid) ON DELETE cascade)");
    if (!bret)
    {
        QSqlError sqlerror = setquery.lastError();
        QString texterr = sqlerror.text();
        if (texterr.contains("already exists",Qt::CaseInsensitive))
            bret = true;
        else
        {
            return bret;
        }
    }
    return bret;
}

mysql.h

#ifndef MYSQL_H
#define MYSQL_H

#include <QtWidgets/QMainWindow>
#include <QSqlQueryModel>
#include "ui_mysql.h"

class mysql : public QMainWindow
{
    Q_OBJECT

public:
    mysql(QWidget *parent = 0);
    ~mysql();

private slots:
    void on_insertButton_clicked();
    void on_deleteButton_clicked();
    void on_updateButton_clicked();

private:
    void reflushModel();
    void setAttibutes(QTableView* pView,int nHeaderHeight = 45,int nColumnHeight = 45);

private:
    Ui::mysqlClass ui;
    QSqlQueryModel m_goodsmodel;
    QSqlQueryModel m_barcodemodel;
};

#endif // MYSQL_H

mysql.cpp

#include "mysql.h"
#include <QSqlError>
#include <QSqlQuery>
#include <QScrollBar>

mysql::mysql(QWidget *parent)
    : QMainWindow(parent)
{
    ui.setupUi(this);

    m_goodsmodel.setQuery("select * from tb_goods",QSqlDatabase::database("file",true));
    m_goodsmodel.setHeaderData(0,Qt::Horizontal,QStringLiteral("id"));
    m_goodsmodel.setHeaderData(1,QStringLiteral("名称"));

    m_barcodemodel.setQuery("select * from tb_barcode",true));
    m_barcodemodel.setHeaderData(0,QStringLiteral("id"));
    m_barcodemodel.setHeaderData(1,QStringLiteral("扫描码"));
    m_barcodemodel.setHeaderData(2,QStringLiteral("rfid"));

    ui.goodView->setModel(&m_goodsmodel);
    ui.skuidView->setModel(&m_barcodemodel);
    setAttibutes(ui.goodView);
    setAttibutes(ui.skuidView);
}

mysql::~mysql()
{
}

void mysql::on_insertButton_clicked()
{
    QSqlQuery setquery(QSqlDatabase::database("file",true));
    setquery.exec("insert into tb_goods values('123456789','aaa')");
    setquery.exec("insert into tb_goods values('23456789','aaeffdda')");

    setquery.exec("insert into tb_barcode(barcode,rfid) values('adddaeee','123456789')");
    reflushModel();
}

//这里应该问题不是很大
void mysql::on_deleteButton_clicked()
{
    QSqlQuery setquery(QSqlDatabase::database("file",true));
    setquery.exec("delete from tb_goods where rfid='123456789'");
    reflushModel();
}

void mysql::on_updateButton_clicked()
{
    QSqlQuery setquery(QSqlDatabase::database("file",true));
    setquery.exec("update tb_goods set name='redddd' where rfid='123456789'");

    reflushModel();
}

void mysql::reflushModel()
{
    m_goodsmodel.setQuery("select * from tb_goods",true));
    m_barcodemodel.setQuery("select * from tb_barcode",true));
}

void mysql::setAttibutes(QTableView* pView,int nHeaderHeight,int nColumnHeight)
{
    if ( pView == NULL )
    {
        QString strTemp = QStringLiteral("pView== NULL！设置表格属性失败！");
        return;
    }

    pView->horizontalHeader()->setFixedHeight(nHeaderHeight);               //设置表头的高度
    pView->horizontalHeader()->setSectionsClickable(false);                 //设置表头不可点击（默认点击后进行排序）
    pView->horizontalHeader()->setStretchLastSection(true);                 //最后一列占满剩余空白
    pView->setSelectionBehavior(QAbstractItemView::SelectRows);             //设置选择行为时每次选择一行    
    pView->setEditTriggers(QAbstractItemView::NoEditTriggers);              //使表视图只读    
    pView->verticalHeader()->setDefaultSectionSize(nColumnHeight);          //设置行高
    pView->setAlternatingRowColors(true);                                   //可以交替颜色显示
    pView->setShowGrid(false);                                              //设置不显示格子线
    pView->setCornerButtonEnabled(false);                                   //左上角的按钮不可用，此按钮功能，一点击，全选

    pView->horizontalScrollBar()->setStyleSheet(
        "QScrollBar:horizontal{height:10px;background:transparent;background-color:rgb(248,248,248);margin:0px,0px,0px;padding-left:10px;padding-right:10px;}"
        "QScrollBar::handle:horizontal{height:10px;background:lightgray;border-radius:5px;/*min-height:20;*/}"
        "QScrollBar::handle:horizontal:hover{height:10px;background:gray;border-radius:5px;/*min-height:20;*/}"
        "QScrollBar::add-line:horizontal{/*height:10px;width:10px;*/border-image:url(:/button/images/button/right.png);/*subcontrol-position:right;*/}"
        "QScrollBar::sub-line:horizontal{/*height:10px;width:10px;*/border-image:url(:/button/images/button/left.png);/*subcontrol-position:left;*/}"
        "QScrollBar::add-line:horizontal:hover{/*height:10px;width:10px;*/border-image:url(:/button/images/button/right_mouseDown.png);/*subcontrol-position:right;*/}"
        "QScrollBar::sub-line:horizontal:hover{/*height:10px;width:10px;*/border-image:url(:/button/images/button/left_mouseDown.png);/*subcontrol-position:left;*/}"
        "QScrollBar::add-page:horizontal,QScrollBar::sub-page:horizontal{background:transparent;border-radius:5px;}"
        );

    pView->verticalScrollBar()->setStyleSheet(
        "QScrollBar:vertical{width:10px;background:transparent;background-color:rgb(248,0px;padding-top:10px;padding-bottom:10px;}"
        "QScrollBar::handle:vertical{width:10px;background:lightgray ;border-radius:5px;min-height:20;}"
        "QScrollBar::handle:vertical:hover{width:10px;background:gray;border-radius:5px;min-height:20;}"
        "QScrollBar::add-line:vertical{height:10px;width:10px;border-image:url(:/button/images/button/down.png);subcontrol-position:bottom;}"
        "QScrollBar::sub-line:vertical{height:10px;width:10px;border-image:url(:/button/images/button/up.png);subcontrol-position:top;}"
        "QScrollBar::add-line:vertical:hover{height:10px;width:10px;border-image:url(:/button/images/button/down_mouseDown.png);subcontrol-position:bottom;}"
        "QScrollBar::sub-line:vertical:hover{height:10px;width:10px;border-image:url(:/button/images/button/up_mouseDown.png);subcontrol-position:top;}"
        "QScrollBar::add-page:vertical,QScrollBar::sub-page:vertical{background:transparent;border-radius:5px;}"
        );
}

4.备注

1.完整的代码下载http://download.csdn.net/detail/zhang_ruiqiang/8939977

2.还存在的问题使用自带的自增作为主键可能会出现越界的问题，不过integer最大为9223372036854775807如果数据量不是很大的话可以不必考虑

3.在vs2010+qt 5.40 + win7下编译通过

4.参考http://bbs.csdn.net/topics/391065975

（编辑：李大同）

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