Python&MySQL&PyQt

Posted 2022-12-13 qq_784583650

环境：
Python2.7+mysql5.6+PyQt4

简单的图形化界面操作数据库：模仿写一个类似于navicat完成可视化检索功能的界面，利用PyQt可视化编程快速完成界面设计，这点比Tkinter设计要简单；

1.利用PyQt进行界面设计：
打开PyQt，新建，选择Main Window，选择左端的控件拖动完成界面的设计，选中元素，可以从右侧查看元素的信息以及修改其属性值，下面贴上设计图：

在设计界面中选中元素双击，可以修改其属性名，添加text，改变显示字符格式等；

2.设计完成后，保存为.ui文件，接下来将其转换为.py文件：
打开cmd：进入PyQt安装目录：
Lib\\site-packages\\PyQt4\\uic>
键入命令格式：
python pyuic.py -o .py文件目录+文件名 .ui文件目录+文件名

我保存的.ui文件放在D盘根目录中，生成的.py文件命名为nihao0.py

3.打开Python运行.py，查看界面
在原有的代码基础上添加下列代码：

import sys

class MyWindow(QtGui.QMainWindow,Ui_MainWindow):#PyQt生产的是一个叫做Ui_MainWindow的类，只需要放在一个框架下画出来即可；
    def __init__(self):
        super(MyWindow,self).__init__()
        self.setupUi(self)

if __name__=="__main__":
    app=QtGui.QApplication(sys.argv)#建立一个app，把框架放在这个app中执行
    app.aboutToQuit.connect(app.deleteLater)
    myshow=MyWindow()
    myshow.show()
    sys.exit(app.exec_())#也可以写成app.exec_() sys.exit(0)，前者是循环整个界面，后者是退出app

运行结果：

这时我们得到了一个我们想得到的界面，只需要往这个界面中添加各种事件即可；

4.动态生成SQL语句——准备
新建数据库mysql，和表格students,表格的属性为
DDL为：

CREATE TABLE `students` (
  `Sid` char(10) NOT NULL,
  `Sname` char(10) DEFAULT NULL,
  `Sage` int(3) DEFAULT NULL,
  `Ssex` char(4) DEFAULT NULL,
  `Sclass` char(7) DEFAULT NULL,
  `Sdept` char(10) DEFAULT NULL,
  `Saddr` char(40) DEFAULT NULL,
  PRIMARY KEY (`Sid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

先写好句柄：

sqlsting="select * from students where "

然后写一个clicked()事件，点击查询的时候，根据用户输入动态构造SQL语句
使用到的方法主要有：
是否选择复选框：checked()
读入输入：text()

5.动态生成SQL语句——字符串构造
构造技巧：
是否需要加and：如果前面已经有了原子公式，需要增加and，否则不加，使用一个flag即可；
是否需要加引号：字符型需要加引号，数字不需要加；
数字类型需要先转换为字符类型：当为数字类型转换为字符型str()，判断数据类型type()，其实可以不写，因为从界面返回的都是QtString类型的数据；
判断什么时候使用Like(字符串匹配问题%)：字符串方法.find("%")，返回值是第一个%出现的位置，如果%不存在，则返回-1；

6.界面显示问题
self.sql_out = QtGui.QTextBrowser(self.centralwidget)：显示框使用方法：
.setText(str)：清除原来数据，显示新的字符串
.append(str)：在末尾添加新的字符串
self.result_out = QtGui.QTableWidget(self.centralwidget)：表格框使用方法：
.setItem(i,j,newItem)：将newItem放在第i行，第j列，注意ij都从0开始；
newItem的声明格式为newItem = QtGui.QTableWidgetItem(str)，即在(i,j)位置显示str
注意QTableWidget只能显示字符串，不能显示数字，所有在显示数据前，需要判断是否为数字：
解决方法：type()以及str()

7.数据库连接问题：
详细在Python&MySQL中已经讲述清除，可以作参考

8.贴上Python代码及运行结果：

# -*- coding: utf-8 -*-
# Form implementation generated from reading ui file 'D:/nihao.ui'
#
# Created: Fri Apr 01 15:28:59 2016
#      by: PyQt4 UI code generator 4.11.3
#
# WARNING! All changes made in this file will be lost!

from PyQt4 import QtCore, QtGui
import sys
import MySQLdb

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        
        self.conn=MySQLdb.connect(
            host='localhost',
            user='root',
            passwd='',
            db='mysql',
            #
            charset='utf8',
        )
        self.cur=self.conn.cursor()
        
        self.sqlstring="select * from students where "
        MainWindow.setObjectName(_fromUtf8("MainWindow"))
        MainWindow.resize(760, 440)
        self.centralwidget = QtGui.QWidget(MainWindow)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.frame = QtGui.QFrame(self.centralwidget)
        self.frame.setGeometry(QtCore.QRect(10, 10, 491, 121))
        self.frame.setFrameShape(QtGui.QFrame.StyledPanel)
        self.frame.setFrameShadow(QtGui.QFrame.Raised)
        self.frame.setObjectName(_fromUtf8("frame"))
        self.check_Sid = QtGui.QCheckBox(self.frame)
        self.check_Sid.setGeometry(QtCore.QRect(20, 10, 71, 16))
        self.check_Sid.setObjectName(_fromUtf8("check_Sid"))
        self.check_Sage = QtGui.QCheckBox(self.frame)
        self.check_Sage.setGeometry(QtCore.QRect(20, 70, 71, 16))
        self.check_Sage.setObjectName(_fromUtf8("check_Sage"))
        self.check_Sname = QtGui.QCheckBox(self.frame)
        self.check_Sname.setGeometry(QtCore.QRect(20, 40, 71, 16))
        self.check_Sname.setObjectName(_fromUtf8("check_Sname"))
        self.check_Ssex = QtGui.QCheckBox(self.frame)
        self.check_Ssex.setGeometry(QtCore.QRect(20, 100, 71, 16))
        self.check_Ssex.setObjectName(_fromUtf8("check_Ssex"))
        self.Sid = QtGui.QLineEdit(self.frame)
        self.Sid.setGeometry(QtCore.QRect(90, 10, 113, 16))
        self.Sid.setObjectName(_fromUtf8("Sid"))
        self.Sname = QtGui.QLineEdit(self.frame)
        self.Sname.setGeometry(QtCore.QRect(90, 40, 113, 16))
        self.Sname.setObjectName(_fromUtf8("Sname"))
        self.first_Sage = QtGui.QLineEdit(self.frame)
        self.first_Sage.setGeometry(QtCore.QRect(90, 70, 41, 16))
        self.first_Sage.setObjectName(_fromUtf8("first_Sage"))
        self.Ssex = QtGui.QLineEdit(self.frame)
        self.Ssex.setGeometry(QtCore.QRect(90, 100, 113, 16))
        self.Ssex.setObjectName(_fromUtf8("Ssex"))
        self.label = QtGui.QLabel(self.frame)
        self.label.setGeometry(QtCore.QRect(140, 70, 16, 16))
        self.label.setObjectName(_fromUtf8("label"))
        self.last_Sage = QtGui.QLineEdit(self.frame)
        self.last_Sage.setGeometry(QtCore.QRect(160, 70, 41, 16))
        self.last_Sage.setObjectName(_fromUtf8("last_Sage"))
        self.check_Sdept = QtGui.QCheckBox(self.frame)
        self.check_Sdept.setGeometry(QtCore.QRect(270, 40, 71, 16))
        self.check_Sdept.setObjectName(_fromUtf8("check_Sdept"))
        self.Sdept = QtGui.QLineEdit(self.frame)
        self.Sdept.setGeometry(QtCore.QRect(340, 40, 113, 16))
        self.Sdept.setObjectName(_fromUtf8("Sdept"))
        self.Sclass = QtGui.QLineEdit(self.frame)
        self.Sclass.setGeometry(QtCore.QRect(340, 10, 113, 16))
        self.Sclass.setObjectName(_fromUtf8("Sclass"))
        self.check_Sclass = QtGui.QCheckBox(self.frame)
        self.check_Sclass.setGeometry(QtCore.QRect(270, 10, 71, 16))
        self.check_Sclass.setObjectName(_fromUtf8("check_Sclass"))
        self.Saddr = QtGui.QLineEdit(self.frame)
        self.Saddr.setGeometry(QtCore.QRect(340, 70, 113, 16))
        self.Saddr.setObjectName(_fromUtf8("Saddr"))
        self.check_Saddr = QtGui.QCheckBox(self.frame)
        self.check_Saddr.setGeometry(QtCore.QRect(270, 70, 71, 16))
        self.check_Saddr.setObjectName(_fromUtf8("check_Saddr"))
        self.find = QtGui.QPushButton(self.frame)
        self.find.setGeometry(QtCore.QRect(380, 100, 75, 21))
        self.find.setObjectName(_fromUtf8("find"))
        self.sql_out = QtGui.QTextBrowser(self.centralwidget)
        self.sql_out.setGeometry(QtCore.QRect(10, 140, 740, 61))
        self.sql_out.setObjectName(_fromUtf8("sql_out"))
        self.result_out = QtGui.QTableWidget(self.centralwidget)
        self.result_out.setEditTriggers(QtGui.QAbstractItemView.NoEditTriggers)#不可编辑表格 
        self.result_out.setGeometry(QtCore.QRect(10, 210, 740, 171))
        self.result_out.setObjectName(_fromUtf8("result_out"))
        self.result_out.setColumnCount(7)
        self.result_out.setRowCount(10)
        self.result_out.resizeColumnsToContents()
        self.result_out.resizeRowsToContents()
        item = QtGui.QTableWidgetItem()
        self.result_out.setHorizontalHeaderItem(0, item)
        item = QtGui.QTableWidgetItem()
        self.result_out.setHorizontalHeaderItem(1, item)
        item = QtGui.QTableWidgetItem()
        self.result_out.setHorizontalHeaderItem(2, item)
        item = QtGui.QTableWidgetItem()
        self.result_out.setHorizontalHeaderItem(3, item)
        item = QtGui.QTableWidgetItem()
        self.result_out.setHorizontalHeaderItem(4, item)
        item = QtGui.QTableWidgetItem()
        self.result_out.setHorizontalHeaderItem(5, item)
        item = QtGui.QTableWidgetItem()
        self.result_out.setHorizontalHeaderItem(6, item)
        self.result_out.horizontalHeader().setDefaultSectionSize(100)
        self.result_out.horizontalHeader().setMinimumSectionSize(25)
        self.result_out.verticalHeader().setDefaultSectionSize(30)
        self.pushButton_2 = QtGui.QPushButton(self.centralwidget)
        self.pushButton_2.setGeometry(QtCore.QRect(675, 390, 75, 21))
        self.pushButton_2.setObjectName(_fromUtf8("pushButton_2"))
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtGui.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 509, 23))
        self.menubar.setObjectName(_fromUtf8("menubar"))
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtGui.QStatusBar(MainWindow)
        self.statusbar.setObjectName(_fromUtf8("statusbar"))
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
        self.check_Sid.setText(_translate("MainWindow", "学号", None))
        self.check_Sage.setText(_translate("MainWindow", "年龄自", None))
        self.check_Sname.setText(_translate("MainWindow", "姓名", None))
        self.check_Ssex.setText(_translate("MainWindow", "性别", None))
        self.label.setText(_translate("MainWindow", "到", None))
        self.check_Sdept.setText(_translate("MainWindow", "系", None))
        self.check_Sclass.setText(_translate("MainWindow", "班级", None))
        self.check_Saddr.setText(_translate("MainWindow", "地址", None))
        self.find.setText(_translate("MainWindow", "查询", None))
        self.sql_out.setText(self.sqlstring)
        item = self.result_out.horizontalHeaderItem(0)
        item.setText(_translate("MainWindow", "Sid", None))
        item = self.result_out.horizontalHeaderItem(1)
        item.setText(_translate("MainWindow", "Sname ", None))
        item = self.result_out.horizontalHeaderItem(2)
        item.setText(_translate("MainWindow", "Sage", None))
        item = self.result_out.horizontalHeaderItem(3)
        item.setText(_translate("MainWindow", "Ssex", None))
        item = self.result_out.horizontalHeaderItem(4)
        item.setText(_translate("MainWindow", "Sclass", None))
        item = self.result_out.horizontalHeaderItem(5)
        item.setText(_translate("MainWindow", "Sdept", None))
        item = self.result_out.horizontalHeaderItem(6)
        item.setText(_translate("MainWindow", "Saddr", None))
        self.pushButton_2.setText(_translate("MainWindow", "退出", None))
    def mousePressEvent(self,event):
        if event.self.find()==QtCore.Qt.LeftButton:
            print "nihao"
    
    def buttonTest(self):
        temp_sqlstring=self.sqlstring
        is_first = True
        if self.check_Sid.isChecked():
            mystr = self.Sid.text()
            if is_first:
                is_first = False
                if mystr.find("%")==-1:
                    temp_sqlstring += "Sid = '" + self.Sid.text() + "'"
                else:
                    temp_sqlstring += "Sid like '" + self.Sid.text() + "'"
            else:
                if mystr.find("%")==-1:
                    temp_sqlstring += " and Sid = '" + self.Sid.text() + "'"
                else:
                    temp_sqlstring += " and Sid like '" + self.Sid.text() + "'"
        
        if self.check_Sname.isChecked():
            if is_first:
                mystr =self.Sname.text()
                is_first = False
                if mystr.find("%")==-1:
                    temp_sqlstring += "Sname = '" + self.Sname.text() + "'"
                else:
                    temp_sqlstring += "Sname like '" + self.Sname.text() + "'"
            else:
                if mystr.find("%")==-1:
                    temp_sqlstring += " and Sname = '" + self.Sname.text() + "'"
                else:
                    temp_sqlstring += " and Sname like '" + self.Sname.text() + "'"
        
        if self.check_Sage.isChecked():
            if is_first:
                is_first = False
                temp_sqlstring += "Sage >= " + self.first_Sage.text() +\\
                " and Sage <= " + self.last_Sage.text()
            else:
                temp_sqlstring += " and Sage >= " + self.first_Sage.text() +\\
                " and Sage <= " + self.last_Sage.text()
        
        if self.check_Ssex.isChecked():
            if is_first:
                is_first = False
                temp_sqlstring += "Ssex = '" + self.Ssex.text() + "'"
            else:
                temp_sqlstring += " and Ssex = '" + self.Ssex.text() + "'"
        
        if self.check_Sclass.isChecked():
            if is_first:
                mystr = self.Sclass.text()
                is_first = False
                if mystr.find("%")==-1:
                    temp_sqlstring += "Sclass = '" + self.Sclass.text() + "'"
                else:
                    temp_sqlstring += "Sclass like '" + self.Sclass.text() + "'"
            else:
                if mystr.find("%")==-1:
                    temp_sqlstring += " and Sclass = '" + self.Sclass.text() + "'"
                else:
                    temp_sqlstring += " and Sclass like '" + self.Sclass.text() + "'"
                    
        if self.check_Sdept.isChecked():
            if is_first:
                mystr = self.Sdept.text()
                is_first = False
                if mystr.find("%")==-1:
                    temp_sqlstring += "Sdept = '" + self.Sdept.text() + "'"
                else:
                    temp_sqlstring += "Sdept like '" + self.Sdept.text() + "'"
            else:
                if mystr.find("%")==-1:
                    temp_sqlstring += " and Sdept = '" + self.Sdept.text() + "'"
                else:
                    temp_sqlstring += " and Sdept like '" + self.Sdept.text() + "'"
        
        if self.check_Saddr.isChecked():
            if is_first:
                mystr = self.Saddr.text()
                is_first = False
                if mystr.find("%")==-1:
                    temp_sqlstring += "Saddr = '" + self.Saddr.text() + "'"
                else:
                    temp_sqlstring +=" and Saddr like '" + self.Saddr.text() + "'"
            else:
                if mystr.find("%")==-1:
                    temp_sqlstring += " and Saddr = '" + self.Saddr.text() + "'"
                else:
                    temp_sqlstring +=" and Saddr like '" + self.Saddr.text() + "'"
        
        self.result_out.clearContents()#每一次查询时清除表格中信息
        if not(is_first):
            self.cur.execute(temp_sqlstring)
            k=0
            for i in self.cur:
                w=0
                for j in i:
                    if type(j)==long:
                        newItem = QtGui.QTableWidgetItem(str(j))
                    else:
                        newItem = QtGui.QTableWidgetItem(j)
                    self.result_out.setItem(k,w,newItem)
                    w += 1
                k +=1
            
        self.sql_out.setText("")
        self.sql_out.append(temp_sqlstring)
        print "find button pressed"
    
    def buttonExit(self):
        self.conn.commit()
        self.cur.close()
        self.conn.close()
        self.close()
    
    def keyPressEvent(self, e):
        if e.key() == QtCore.Qt.Key_Escape:
            self.buttonExit()
        
class MyWindow(QtGui.QMainWindow,Ui_MainWindow):
    def __init__(self):
        super(MyWindow,self).__init__()
        self.setupUi(self)
        self.connect(self.find, QtCore.SIGNAL('clicked()'), self.buttonTest)
        self.connect(self.pushButton_2,QtCore.SIGNAL('clicked()'),self.buttonExit)

if __name__=="__main__":
    app=QtGui.QApplication(sys.argv)
    app.aboutToQuit.connect(app.deleteLater)
    myshow=MyWindow()
    myshow.show()
    sys.exit(app.exec_())
    #app.exec_()
    #sys.exit(0)

注：运行前首先确保已经在MySQL中存在mysql数据库以及students表格；
运行结果：

由于原来设计的界面比较小，后来改变了各个控件的长宽；
这样就完成的简单的界面化动态构造SQL语句，并将结果返回界面显示功能；