Qt数据库-QSqlRelationalTableModel

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基本理论

QSqlTableModel与QSqlRelationalTableModel，它们没有太大的不同，唯一的就是后者在前者的基础之上添加了外键（或者叫外码）的支持。
QSqlRelationalTableModel，该类为单张的数据库表提供了一个可编辑的数据模型，它支持外键。

参考代码：

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QtSql/QSqlQuery>
#include<QtSql/QSqlDatabase>
#include<QtSql/QSqlRelationalTableModel>
namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

private:
    Ui::Widget *ui;
    QSqlRelationalTableModel *model;
};
static bool createConnection()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("database.db");
    if(!db.open()) return false;
    QSqlQuery query;
    query.exec("create table student (id int primary key, name vchar,course int)");
    query.exec("insert into student values (1,'yafei0',1)");
    query.exec("insert into student values (2,'yafei1',1)");
    query.exec("insert into student values (3,'yafei2',2)");
    query.exec("create table course (id int primary key, name vchar, teacher vchar)");
    query.exec("insert into course values (1,'Math','yafeilinux1')");
    query.exec("insert into course values (2,'English','yafeilinux2')");
    query.exec("insert into course values (3,'Computer','yafeilinux3')");
    return true;
}
#endif // WIDGET_H

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    model = new QSqlRelationalTableModel(this);
    model->setEditStrategy(QSqlTableModel::OnFieldChange); //属性变化时写入数据库
    model->setTable("student");
    model->setRelation(2,QSqlRelation("course","id","name"));
    //将student表的第三个属性设为course表的id属性的外键，并将其显示为course表的name属性的值
    model->setHeaderData(0, Qt::Horizontal, QObject::tr("ID"));
    model->setHeaderData(1, Qt::Horizontal, QObject::tr("Name"));
    model->setHeaderData(2, Qt::Horizontal, QObject::tr("Course"));
    model->select();
    ui->tableView->setModel(model);
}

Widget::~Widget()
{
    delete ui;
}

实验结果