数据库存储树形数据，并提供操作界面QTreeView

我会带着你远行 2023-01-19 11:53 2阅读 0赞

一个简单的树形数据存储在数据库，然后用Qt 进行界面显示和添加、删除、编辑的例子

存储数据采用id,pid形式，(sn表示兄弟中的排行,但未实现)

读取数据库数据添加到QTreeView,调用了递归函数。

删除节点，只允许没有子节点的结对被删除，避免操作失误。

下图是数据库结构和软件界面。

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#ifndef WIDGET_H
    #define WIDGET_H
    
    #include <QWidget>
    #include <QStandardItemModel>
    #include <QStringList>
    #include <QSqlDatabase> //QSqlQuery
    #include <QSqlQuery>
    
    #include <QMessageBox>
    #include <QSqlError>
    #include <QHeaderView>
    
    
    namespace Ui {
    class Widget;
    }
    
    class Widget : public QWidget
    {
        Q_OBJECT
    
    public:
        explicit Widget(QWidget *parent = 0);
        ~Widget();
    
        QStandardItemModel *stdModel;
    
    private slots:
    
        void on_Add();
        void on_Delete();
        void on_Edit(QStandardItem*);
        void onTreeClicked(const QModelIndex &);
    
        bool openDB();//打开数据库
      //  void initModel();
       void  fillModelFromDB();//数据库内容填充模型
       void addSonToModel(int pid,QStandardItem* parent);//递归函数，把子项添加到父项，pid ,parent 分别是上级ID和项
    
    
    private:
        Ui::Widget *ui;
          QSqlDatabase db;
         // QStandardItemModel *stdModel;
    
        void initTree();
       // void initTreeB();
    };
    
    #endif // WIDGET_H

#include "widget.h"
    #include "ui_widget.h"
    
    Widget::Widget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::Widget)
    {
        ui->setupUi(this);    
        openDB();
      fillModelFromDB();
      initTree();
      // initTree();
       connect(ui->treeView,SIGNAL(clicked(const QModelIndex &)),this,SLOT(onTreeClicked(const QModelIndex &)));
       connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(on_Add()));
        connect(ui->pushButton_2,SIGNAL(clicked()),this,SLOT(on_Delete()));
        // connect(ui->pushButton_3,SIGNAL(clicked()),this,SLOT(on_Edit()));
          connect(stdModel,SIGNAL(itemChanged(QStandardItem*)),this,SLOT(on_Edit(QStandardItem*)));
        // itemChanged
    
    }
    
    Widget::~Widget()
    {
        delete ui;
    }
    
    void Widget::onTreeClicked(const QModelIndex & index)
    {
    
      //  stdModel->index()
      //   QStandardItem *item = stdModel->itemFromIndex(index);
        QString str=QString("rowid: %1, colid:%2").arg(index.row()).arg(index.column());
         ui->label->setText(str);
    }
    
    //add
    void Widget::on_Add()
    {
       int theid=-2;
       int pid=-2;
       QString theName("AddItem");//为方便起见，固定名称
    
        QSqlQuery query(db);
        query.exec("SELECT max(ID)  FROM Product");
           if(query.size()==0)
            theid=1;
        else
        {
            query.next();
          theid = 1+query.value(0).toInt();}
    
    
        QStandardItem *root= stdModel->invisibleRootItem();
        QModelIndex index = ui->treeView->currentIndex();//当前选中
         QStandardItem *pitem = stdModel->itemFromIndex(index);
         if(!pitem)
         {
             pid=0;
             pitem=root;  //若未选中，则添加到根目录         
         }else{
             pid=pitem->data().toInt();
         }
    
         QString qreryString=
                 QString("insert into Product(ID,PID,sNAME) values(%1,%2,'%3') ").arg(theid).arg(pid).arg(theName);
        query.exec(qreryString);
                  //   int zhepid=
             QStandardItem* item1 = new QStandardItem("AddName");
             item1->setData(QVariant(theid));
             pitem->appendRow(item1);
               ui->treeView->resizeColumnToContents(0);
              //stdModel->appendRow()
    }
    
    
    //delete
    void Widget::on_Delete()
    {
    
        QModelIndex index = ui->treeView->currentIndex();//当前选中
        if(!index.isValid())
            return ;
        if(index.child(0,0).isValid())
            return;
        //若无子节点，则可以删除
    
        QStandardItem *pitem = stdModel->itemFromIndex(index);
        int myid=pitem->data().toInt();
        QSqlQuery query(db);
        QString str=QString("delete from Product where ID=%1").arg(myid);
        if(query.exec(str))
            stdModel->removeRow(index.row(),index.parent());
    
    }
    
    
    
    //edit
    void Widget::on_Edit(QStandardItem* item)
    {
        if(!item)
            return;
        int theID=item->data().toInt();
        QString str=item->text();
         QSqlQuery query(db);
       QString qreryString=
                QString("update  Product set  sName='%1' where ID=%2 ").arg(str).arg(theID);
       query.exec(qreryString);
    
    //    QMessageBox messagebox;
    //    messagebox.setText(" data changed");
    //    messagebox.exec();
    
    }
    
    void   Widget::fillModelFromDB()
    {
    
        stdModel=new QStandardItemModel(this);
        QStandardItem * parent=stdModel->invisibleRootItem();
        addSonToModel(0,parent);
    
    }
    
    void Widget::addSonToModel(int pid,QStandardItem* parent)
      {
          QString qreryString=
                  QString("SELECT ID,PID,sName  FROM Product where pid=%1 ").arg(pid);
    
          QSqlQuery query(qreryString,db);
              while (query.next()) {
                      int id = query.value(0).toInt();
                        QString  name = query.value(2).toString();
                        QStandardItem* item =new QStandardItem(name);
                       item->setData(QVariant(id));
                        parent->appendRow(item);
                        addSonToModel(id, item);
                  }
      }
    
    
    void  Widget::initTree()
    {
            stdModel->setHorizontalHeaderLabels(QStringList()<<QString("TheName") );     //设置列头
           QTreeView* t = ui->treeView;
            //   t->setEditTriggers(QTreeView::NoEditTriggers);			//单元格不能编辑
               t->setSelectionBehavior(QTreeView::SelectRows);			//一次选中整行
               t->setSelectionMode(QTreeView::ContiguousSelection);        //单选，配合上面的整行就是一次选单行
               t->setAlternatingRowColors(true);                       //每间隔一行颜色不一样，当有qss时该属性无效
               t->setFocusPolicy(Qt::NoFocus);                         //去掉鼠标移到单元格上时的虚线框
    
               //2，列头相关设置
           //    t->header()->hide();                                  //隐藏列头
               t->header()->setStretchLastSection(true);               //最后一列自适应宽度
               t->header()->setDefaultAlignment(Qt::AlignCenter);      //列头文字默认居中对齐
    
               t->setAllColumnsShowFocus(1);
              t->setAnimated(true);
    
               // t->setDragDropMode(QAbstractItemView::InternalMove);
             ui->treeView->setModel(stdModel);
    
    
    }
    
    
    bool Widget::openDB()
    {
    
        db = QSqlDatabase::addDatabase("QODBC");
        QString dsn = QString("DRIVER={Microsoft Access Driver (*.mdb, *.accdb)};FIL={MS Access};DBQ=./TreeDB.accdb;");
        db.setDatabaseName(dsn);
        bool result = db.open();
        if(!result)
        {
            QMessageBox messagebox;
            messagebox.setText("Database error");
            messagebox.exec();
            db.close();
        }
        return result;
    }

源代码下载地址：[下载][Link 1]

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[Link 1]: https://download.csdn.net/download/cibiren2011/18475629