9、Qt Project之简单的数据库接口

时间：2022-06-23 15:29:38

简单的数据库接口

 Step1：首先完成整个UI界面的额设计：

<?xml version="1.0" encoding="UTF-8"?>

<ui version="4.0">

 <class>MainWindow</class>

 <widget class="QMainWindow" name="MainWindow">

  <property name="geometry">

   <rect>

    <x>0</x>

    <y>0</y>

    <width>400</width>

    <height>313</height>

   </rect>

  </property>

  <property name="windowTitle">

   <string>MainWindow</string>

  </property>

  <widget class="QWidget" name="centralWidget">

   <widget class="QPushButton" name="pushButton">

    <property name="geometry">

     <rect>

      <x>320</x>

      <y>220</y>

      <width>51</width>

      <height>27</height>

     </rect>

    </property>

    <property name="text">

     <string>Insert</string>

    </property>

   </widget>

   <widget class="QTextEdit" name="textEdit">

    <property name="geometry">

     <rect>

      <x>80</x>

      <y>220</y>

      <width>51</width>

      <height>31</height>

     </rect>

    </property>

   </widget>

   <widget class="QTextEdit" name="textEdit_2">

    <property name="geometry">

     <rect>

      <x>140</x>

      <y>220</y>

      <width>101</width>

      <height>31</height>

     </rect>

    </property>

   </widget>

   <widget class="QTextEdit" name="textEdit_3">

    <property name="geometry">

     <rect>

      <x>250</x>

      <y>220</y>

      <width>61</width>

      <height>31</height>

     </rect>

    </property>

   </widget>

   <widget class="QLabel" name="label">

    <property name="geometry">

     <rect>

      <x>100</x>

      <y>200</y>

      <width>31</width>

      <height>17</height>

     </rect>

    </property>

    <property name="text">

     <string>ID</string>

    </property>

   </widget>

   <widget class="QLabel" name="label_2">

    <property name="geometry">

     <rect>

      <x>170</x>

      <y>200</y>

      <width>65</width>

      <height>17</height>

     </rect>

    </property>

    <property name="text">

     <string>NAME</string>

    </property>

   </widget>

   <widget class="QLabel" name="label_3">

    <property name="geometry">

     <rect>

      <x>260</x>

      <y>200</y>

      <width>65</width>

      <height>17</height>

     </rect>

    </property>

    <property name="text">

     <string>TEMP</string>

    </property>

   </widget>

   <widget class="QLabel" name="label_4">

    <property name="geometry">

     <rect>

      <x>20</x>

      <y>110</y>

      <width>171</width>

      <height>21</height>

     </rect>

    </property>

    <property name="font">

     <font>

      <pointsize>10</pointsize>

      <italic>true</italic>

      <underline>false</underline>

      <strikeout>false</strikeout>

     </font>

    </property>

    <property name="cursor">

     <cursorShape>BlankCursor</cursorShape>

    </property>

    <property name="text">

     <string>Designed by : mm1994uestc</string>

    </property>

    <property name="alignment">

     <set>Qt::AlignCenter</set>

    </property>

   </widget>

   <widget class="QLabel" name="label_5">

    <property name="geometry">

     <rect>

      <x>0</x>

      <y>50</y>

      <width>171</width>

      <height>51</height>

     </rect>

    </property>

    <property name="font">

     <font>

      <pointsize>16</pointsize>

      <italic>true</italic>

      <underline>false</underline>

      <strikeout>false</strikeout>

     </font>

    </property>

    <property name="cursor">

     <cursorShape>BlankCursor</cursorShape>

    </property>

    <property name="text">

     <string>MySQL Control</string>

    </property>

    <property name="alignment">

     <set>Qt::AlignCenter</set>

    </property>

   </widget>

   <widget class="QLabel" name="label_6">

    <property name="geometry">

     <rect>

      <x>0</x>

      <y>0</y>

      <width>321</width>

      <height>51</height>

     </rect>

    </property>

    <property name="font">

     <font>

      <pointsize>28</pointsize>

      <italic>true</italic>

      <underline>false</underline>

      <strikeout>false</strikeout>

     </font>

    </property>

    <property name="cursor">

     <cursorShape>BlankCursor</cursorShape>

    </property>

    <property name="text">

     <string>Qt interface Demo!</string>

    </property>

    <property name="alignment">

     <set>Qt::AlignCenter</set>

    </property>

   </widget>

   <widget class="QLabel" name="label_7">

    <property name="geometry">

     <rect>

      <x>20</x>

      <y>220</y>

      <width>51</width>

      <height>31</height>

     </rect>

    </property>

    <property name="text">

     <string>Insert:</string>

    </property>

   </widget>

   <widget class="QLabel" name="label_8">

    <property name="geometry">

     <rect>

      <x>20</x>

      <y>160</y>

      <width>51</width>

      <height>31</height>

     </rect>

    </property>

    <property name="text">

     <string>Search:</string>

    </property>

   </widget>

   <widget class="QTextEdit" name="SearchInput">

    <property name="geometry">

     <rect>

      <x>80</x>

      <y>160</y>

      <width>101</width>

      <height>31</height>

     </rect>

    </property>

   </widget>

   <widget class="QLabel" name="label_9">

    <property name="geometry">

     <rect>

      <x>100</x>

      <y>140</y>

      <width>65</width>

      <height>17</height>

     </rect>

    </property>

    <property name="text">

     <string>NAME</string>

    </property>

   </widget>

   <widget class="QPushButton" name="pushButton_2">

    <property name="geometry">

     <rect>

      <x>320</x>

      <y>160</y>

      <width>51</width>

      <height>27</height>

     </rect>

    </property>

    <property name="text">

     <string>Search</string>

    </property>

   </widget>

   <widget class="QLabel" name="SearchRes">

    <property name="geometry">

     <rect>

      <x>230</x>

      <y>160</y>

      <width>81</width>

      <height>31</height>

     </rect>

    </property>

    <property name="text">

     <string>Search Res</string>

    </property>

   </widget>

   <widget class="QLabel" name="label_11">

    <property name="geometry">

     <rect>

      <x>180</x>

      <y>160</y>

      <width>65</width>

      <height>31</height>

     </rect>

    </property>

    <property name="font">

     <font>

      <pointsize>22</pointsize>

      <weight>75</weight>

      <bold>true</bold>

     </font>

    </property>

    <property name="text">

     <string>---&gt;</string>

    </property>

   </widget>

   <widget class="QLabel" name="label_10">

    <property name="geometry">

     <rect>

      <x>220</x>

      <y>50</y>

      <width>110</width>

      <height>110</height>

     </rect>

    </property>

    <property name="text">

     <string>              Cover</string>

    </property>

   </widget>

  </widget>

  <widget class="QMenuBar" name="menuBar">

   <property name="geometry">

    <rect>

     <x>0</x>

     <y>0</y>

     <width>400</width>

     <height>25</height>

    </rect>

   </property>

  </widget>

  <widget class="QToolBar" name="mainToolBar">

   <attribute name="toolBarArea">

    <enum>TopToolBarArea</enum>

   </attribute>

   <attribute name="toolBarBreak">

    <bool>false</bool>

   </attribute>

  </widget>

  <widget class="QStatusBar" name="statusBar"/>

 </widget>

 <layoutdefault spacing="6" margin="11"/>

 <resources/>

 <connections/>

</ui>

9、Qt Project之简单的数据库接口界面的设计如右图所示

我们能够分析功能，在search中填入内容之后，点击search按钮就会根据程序中定义使用的mysql数据库的数据库以及表进行数据的查询工作，并将查询的结果输出到右侧的lable当中。

Step2：根据上述分析的MySQ_UI的功能设计，完成槽函数的定义和实现：

首先需要添加sql的核心模块（关于sql模块的安装参考我的另一篇博客：http://www.cnblogs.com/uestc-mm/p/8920525.html）：

QT += core gui sql

下面首先是mainwindow.h文件的内容，包含了头文件：#include <QSqlDatabase>、#include <QSqlQuery>这两个MySQL数据库需要使用到的头文件；

声明定义了SLOT槽函数：void on_pushButton_clicked(bool checked)、void on_pushButton_2_clicked()

定义了私有成员变量db：  QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL")

#ifndef MAINWINDOW_H

#define MAINWINDOW_H

#include <QMainWindow>

#include <QSqlDatabase>

#include <QDebug>

#include <QSqlQuery>

namespace Ui {

class MainWindow;

}

class MainWindow : public QMainWindow

{

    Q_OBJECT

public:

    explicit MainWindow(QWidget *parent = 0);

    ~MainWindow();

private slots:

    void on_pushButton_clicked(bool checked);

    void on_pushButton_2_clicked();

private:

    Ui::MainWindow *ui;

    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL"); // define the db via

};

#endif // MAINWINDOW_H

接着在mainwindow.cpp文件中对变量db进行初始化和MySQL数据库进行连接， 并实现对应的槽函数：

void MainWindow::on_pushButton_clicked(bool checked)

{

    QString ID,NAME,TEMP;

    ID = ui->textEdit->toPlainText(); // Get the input content

    NAME = ui->textEdit_2->toPlainText();

    TEMP = ui->textEdit_3->toPlainText();

    qDebug() << "ID:" << ID << "  " << "NAME:" << NAME << "  " << "TEMP:" << TEMP;

    qDebug() << "Aviliable SQL drivers!";

    QStringList drivers = QSqlDatabase::drivers(); //Getting the support databases,if do not have the database driver,we can not use this databse

    foreach(QString driver,drivers)

        qDebug() << driver;

    if(!db.open()) // Connect to the database

    {

        qDebug() << "failed to connect to the mysql database!";

    }

    else

    {

        qDebug() << "Mysql is successfully Opened!";

    }

    QSqlQuery query(db); //Create a new query for db,use query to change the content

    QString Command_insert[] = {"insert into ","GanSu","BeiJing"," values(",")"};

    QString Command = "";

    Command = Command_insert[]+Command_insert[]+Command_insert[]+ID+","+"\""+NAME+"\""+","+TEMP+Command_insert[]; // Combine the command

    qDebug() << Command;

    query.exec(Command); // excute the command to control the database

}

void MainWindow::on_pushButton_2_clicked()

{

    if(!db.open())

    {

        qDebug() << "failed to connect to the mysql database!";

    }

    else

    {

        qDebug() << "Mysql is successfully Opened!";

    }

    QSqlQuery query(db);

    QString name,command;

    QString Command_search[] = {"select * from GanSu where name=","'"};

    name = ui->SearchInput->toPlainText();

    qDebug() << name;

    command = Command_search[] + Command_search[] + name + Command_search[];

    qDebug() << command;

    query.exec(command);

    while(query.next()) // wait for database finish the command just now

    {

        int val1 = query.value().toInt();

        QString val2 = query.value().toString(); // Getting the content in the query!

        int val3 = query.value().toInt();

        qDebug() << val1 << val2 << val3;

        ui->SearchRes->setText(query.value().toString()+query.value().toString()+query.value().toString());

    }

}

完成上述操作就可以编译运行Qt程序了。

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