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>

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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