QT数据库的简单使用，命令行操作

#include "widget.h" #include "ui_widget.h" #include <QSqlDatabase> #include <QDebug> #include <QSqlQuery> Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget) { ui->setupUi(this); /* QStringList drivers; drivers = QSqlDatabase::drivers(); foreach(QString driver,drivers) qDebug() << driver; */ QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");//设置接入哪种数据库 db.setDatabaseName("dataset.db");//给数据库命名 if(!db.open()) { qDebug() << "创建失败 " << db.lastError();//打印出创建失败的原因 } else { qDebug() << "创建成功"; } QSqlQuery sql_query; /* QString create = "create table student(id int,name varchar(20),age int)"; sql_query.prepare(create); if(!sql_query.exec()) { qDebug() << "创建执行错误： " << sql_query.lastError(); } else { qDebug() << "创建成功"; } */ //第一次运行时应把以上注释取消 QString insert_sql = "insert into student values(?,?,?)" ; sql_query.prepare(insert_sql); sql_query.addBindValue(1); sql_query.addBindValue("Rick"); sql_query.addBindValue(15);//一个？对应一个bindValue if(!sql_query.exec()) { qDebug() << "插入执行错误： " << sql_query.lastError(); } else { qDebug() << "插入成功"; } QString select_sql = "select * from student";//把student的全部内容显示出来 sql_query.prepare(select_sql); if(!sql_query.exec()) { qDebug() << "查看执行错误： " << sql_query.lastError(); } else { while(sql_query.next())//如果下一行数据还存在，就继续执行 { int id = sql_query.value(0).toInt();//将sql里的int转换为qt里的int QString name = sql_query.value(1).toString();//将sql里的string转化为qt里的string int age = sql_query.value(2).toInt(); qDebug() << "id " << id << " name: " << name << " age: " << age; } } /*QString clear_sql = "delete from student"; sql_query.prepare(clear_sql); if(!sql_query.exec()) { qDebug() << "删除错误： " << sql_query.lastError(); } else { qDebug() << "删除成功"; }*/ QString update_sql = "update student set name =:nm where id =:n"; //将ID为n的那一行的name换为nm sql_query.prepare(update_sql); sql_query.bindValue(":nm","MidsgKi");//将nm绑定为MiKi sql_query.bindValue(":n", "1");//将n绑定为1 if(!sql_query.exec()) { qDebug() << "更新失败" << sql_query.lastError(); } else { qDebug() << "更新成功"; } select_sql = "select * from student";//把student的全部内容显示出来 sql_query.prepare(select_sql); if(!sql_query.exec()) { qDebug() << "查看执行错误： " << sql_query.lastError(); } else { while(sql_query.next())//如果下一行数据还存在，就继续执行 { int id1 = sql_query.value(0).toInt();//将sql里的int转换为qt里的int QString name1 = sql_query.value(1).toString();//将sql里的string转化为qt里的string int age1 = sql_query.value(2).toInt(); qDebug() << "id " << id1 << " name: " << name1 << " age: " << age1; } } QString delete1_sql = "delete from student where id = ?"; sql_query.prepare(delete1_sql); sql_query.addBindValue(1); if(!sql_query.exec()) { qDebug() << "删除失败"; } else { qDebug() << "删除成功"; } } Widget::~Widget() { delete ui; }