9、Qt Project之簡單的數據庫接口

本文轉載自查看原文 2018-04-25 19:36 834 基於Qt的界面設計

簡單的數據庫接口

Step1：首先完成整個UI界面的額設計：

<?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>

View Code

界面的設計如右圖所示

我們能夠分析功能，在search中填入內容之后，點擊search按鈕就會根據程序中定義使用的mysql數據庫的數據庫以及表進行數據的查詢工作，並將查詢的結果輸出到右側的lable當中。

Step2：根據上述分析的MySQ_UI的功能設計，完成槽函數的定義和實現：

首先需要添加sql的核心模塊（關於sql模塊的安裝參考我的另一篇博客：http://www.cnblogs.com/uestc-mm/p/8920525.html）：

QT += core gui sql

下面首先是mainwindow.h文件的內容，包含了頭文件：#include <QSqlDatabase>、#include <QSqlQuery>這兩個MySQL數據庫需要使用到的頭文件；

聲明定義了SLOT槽函數：void on_pushButton_clicked(bool checked)、void on_pushButton_2_clicked()

定義了私有成員變量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文件中對變量db進行初始化和MySQL數據庫進行連接，並實現對應的槽函數：

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[0]+Command_insert[1]+Command_insert[3]+ID+","+"\""+NAME+"\""+","+TEMP+Command_insert[4]; // 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[0] + Command_search[1] + name + Command_search[1];

    qDebug() << command;

    query.exec(command);

    while(query.next()) // wait for database finish the command just now
    {
        int val1 = query.value(0).toInt();
        QString val2 = query.value(1).toString(); // Getting the content in the query!
        int val3 = query.value(3).toInt();
        qDebug() << val1 << val2 << val3;

        ui->SearchRes->setText(query.value(0).toString()+query.value(1).toString()+query.value(2).toString());
    }
}

完成上述操作就可以編譯運行Qt程序了。

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