Introduction to PyQt5 (29) SQLite database

table of Contents

1. Operate SQLite database

2. Use a visual way to add, delete, modify and check the SQLite database

Three. Paging display data

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1. Operate SQLite database

Lightweight database, support multiple interfaces, cross-platform

Many mobile applications (eg: Android, iOS) now use SQLite as a local database

The local database only needs to provide the file name, not the IP, user name, password, etc.

Database visualization tool DB Browser for SQLite:

Official website: http://www.sqlitebrowser.org/

Download: http://www.sqlitebrowser.org/dl/

 

Code:

from PyQt5.QtSql import QSqlDatabase,QSqlQuery


def createDB():
    db=QSqlDatabase.addDatabase('QSQLITE')#指定数据库类型
    #指定SQLite数据库文件名
    db.setDatabaseName('./db/muttonDB.db')#muttonDB.db之前的目录都要存在才可建立成功！数据库名字自己随便起
    if not db.open():
        print('无法建立与数据库的连接')
        return False
    query=QSqlQuery()
    query.exec('create table people(id int primary key,name varcahr(10),address varcahr(50))')
    query.exec('insert into people values(1,"李宁","Shenyang")')
    query.exec('insert into people values(2,"超人","克星")')
    db.close()
    return True


if __name__=='__main__':
    createDB()

operation result:

Just open the database.

 

2. Use a visual way to add, delete, modify and check the SQLite database

QTableView
QSql TableModel

 

Code:

import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtSql import *


#初始化
def initializeModel(model):
    model.setTable('people')
    #当字段变化时会触发一些事件
    model.setEditStrategy(QSqlTableModel.OnFieldChange)
    #将整个数据装载到model中
    model.select()
    #设置字段头
    model.setHeaderData(0, Qt.Horizontal,'ID')
    model.setHeaderData(1, Qt.Horizontal, '姓名')
    model.setHeaderData(2, Qt.Horizontal, '地址')


#创建视图
def createView(title,model):
    view = QTableView()
    view.setModel(model)
    view.setWindowTitle(title)
    return view


def findrow(i):
    #当前选中的行
    delrow = i.row()
    print('del row=%s' % str(delrow))


def addrow():
    #不是在QTableView上添加，而是在模型上添加,会自动将数据保存到数据库中！
    # 参数一：数据库共有几行数据  参数二：添加几行
    ret = model.insertRows(model.rowCount(),1)#返回是否插入
    print('数据库共有%d行数据' % model.rowCount())
    print('insertRow=%s' % str(ret))


if __name__ == '__main__':
    app = QApplication(sys.argv)
    db = QSqlDatabase.addDatabase('QSQLITE')
    db.setDatabaseName('./db/muttonDB.db')
    model = QSqlTableModel()#MVC模式中的模型
    delrow = -1
    #初始化将数据装载到模型当中
    initializeModel(model)
    view = createView("展示数据",model)
    view.clicked.connect(findrow)

    dlg = QDialog()
    layout = QVBoxLayout()
    layout.addWidget(view)
    addBtn = QPushButton('添加一行')
    addBtn.clicked.connect(addrow)

    delBtn = QPushButton('删除一行')
    delBtn.clicked.connect(lambda :model.removeRow(view.currentIndex().row()))

    layout.addWidget(view)
    layout.addWidget(addBtn)
    layout.addWidget(delBtn)
    dlg.setLayout(layout)
    dlg.setWindowTitle("Database Demo")
    dlg.resize(500,400)
    dlg.show()
    sys.exit(app.exec())

operation result:

Function self-test    

 

Three. Paging display data

limit keyword

limit n,m

n is the starting point (not included), m is the offset, for example, limit 10, 20 represents 20 data starting from 11, that is, 11-30

 

Code:

import sys
from PyQt5.QtWidgets import*
from PyQt5.QtCore import Qt
from PyQt5.QtSql import *


class DataGrid(QWidget):
    def createTableAndInit(self):
        # 添加数据库
        self.db = QSqlDatabase.addDatabase('QSQLITE')
        # 设置数据库名称
        self.db.setDatabaseName('./db/database.db')
        # 判断是否打开
        if not self.db.open():
            return False

        # 声明数据库查询对象
        query = QSqlQuery()
        # 创建表
        query.exec("create table student(id int primary key, name vchar, sex vchar, age int, deparment vchar)")

        # 添加记录
        query.exec("insert into student values(1,'张三1','男',20,'计算机')")
        query.exec("insert into student values(2,'李四1','男',19,'经管')")
        query.exec("insert into student values(3,'王五1','男',22,'机械')")
        query.exec("insert into student values(4,'赵六1','男',21,'法律')")
        query.exec("insert into student values(5,'小明1','男',20,'英语')")
        query.exec("insert into student values(6,'小李1','女',19,'计算机')")
        query.exec("insert into student values(7,'小张1','男',20,'机械')")
        query.exec("insert into student values(8,'小刚1','男',19,'经管')")
        query.exec("insert into student values(9,'张三2','男',21,'计算机')")
        query.exec("insert into student values(10,'张三3','女',20,'法律')")
        query.exec("insert into student values(11,'王五2','男',19,'经管')")
        query.exec("insert into student values(12,'张三4','男',20,'计算机')")
        query.exec("insert into student values(13,'小李2','男',20,'机械')")
        query.exec("insert into student values(14,'李四2','女',19,'经管')")
        query.exec("insert into student values(15,'赵六3','男',21,'英语')")
        query.exec("insert into student values(16,'李四2','男',19,'法律')")
        query.exec("insert into student values(17,'小张2','女',22,'经管')")
        query.exec("insert into student values(18,'李四3','男',21,'英语')")
        query.exec("insert into student values(19,'小李3','女',19,'法律')")
        query.exec("insert into student values(20,'王五3','女',20,'机械')")
        query.exec("insert into student values(21,'张三4','男',22,'计算机')")
        query.exec("insert into student values(22,'小李2','男',20,'法律')")
        query.exec("insert into student values(23,'张三5','男',19,'经管')")
        query.exec("insert into student values(24,'小张3','女',20,'计算机')")
        query.exec("insert into student values(25,'李四4','男',22,'英语')")
        query.exec("insert into student values(26,'赵六2','男',20,'机械')")
        query.exec("insert into student values(27,'小李3','女',19,'英语')")
        query.exec("insert into student values(28,'王五4','男',21,'经管')")

        return True

    def __init__(self):
        super().__init__()
        self.setWindowTitle("分页查询例子")
        self.resize(750, 350)
        self.createTableAndInit()

        # 当前页
        self.currentPage = 0
        # 总页数
        self.totalPage = 0
        # 总记录数
        self.totalRecrodCount = 0
        # 每页显示记录数
        self.PageRecordCount = 6

        self.initUI()

    def initUI(self):
        # 创建窗口
        self.createWindow()
        # 设置表格
        self.setTableView()

        # 信号槽连接
        self.prevButton.clicked.connect(self.onPrevButtonClick)
        self.nextButton.clicked.connect(self.onNextButtonClick)
        self.switchPageButton.clicked.connect(self.onSwitchPageButtonClick)

    def closeEvent(self, event):
        # 关闭数据库
        self.db.close()

    # 创建窗口
    def createWindow(self):
        # 操作布局
        operatorLayout = QHBoxLayout()
        self.prevButton = QPushButton("前一页")
        self.nextButton = QPushButton("后一页")
        self.switchPageButton = QPushButton("Go")
        self.switchPageLineEdit = QLineEdit()
        self.switchPageLineEdit.setFixedWidth(40)

        switchPage = QLabel("转到第")
        page = QLabel("页")
        operatorLayout.addWidget(self.prevButton)
        operatorLayout.addWidget(self.nextButton)
        operatorLayout.addWidget(switchPage)
        operatorLayout.addWidget(self.switchPageLineEdit)
        operatorLayout.addWidget(page)
        operatorLayout.addWidget(self.switchPageButton)
        operatorLayout.addWidget(QSplitter())

        # 状态布局
        statusLayout = QHBoxLayout()
        self.totalPageLabel = QLabel()
        self.totalPageLabel.setFixedWidth(70)
        self.currentPageLabel = QLabel()
        self.currentPageLabel.setFixedWidth(70)

        self.totalRecordLabel = QLabel()
        self.totalRecordLabel.setFixedWidth(70)

        statusLayout.addWidget(self.totalPageLabel)
        statusLayout.addWidget(self.currentPageLabel)
        statusLayout.addWidget(QSplitter())
        statusLayout.addWidget(self.totalRecordLabel)

        # 设置表格属性
        self.tableView = QTableView()
        # 表格宽度的自适应调整
        self.tableView.horizontalHeader().setStretchLastSection(True)
        self.tableView.horizontalHeader().setSectionResizeMode(QHeaderView.Stretch)

        # 创建界面
        mainLayout = QVBoxLayout(self);
        mainLayout.addLayout(operatorLayout);
        mainLayout.addWidget(self.tableView);
        mainLayout.addLayout(statusLayout);
        self.setLayout(mainLayout)

    # 设置表格
    def setTableView(self):

        # 声明查询模型
        self.queryModel = QSqlQueryModel(self)
        # 设置当前页
        self.currentPage = 1;
        # 得到总记录数
        self.totalRecrodCount = self.getTotalRecordCount()
        # 得到总页数
        self.totalPage = self.getPageCount()
        # 刷新状态
        self.updateStatus()
        # 设置总页数文本
        self.setTotalPageLabel()
        # 设置总记录数
        self.setTotalRecordLabel()

        # 记录查询
        self.recordQuery(0)
        # 设置模型
        self.tableView.setModel(self.queryModel)

        print('totalRecrodCount=' + str(self.totalRecrodCount))
        print('totalPage=' + str(self.totalPage))

        # 设置表格表头
        self.queryModel.setHeaderData(0, Qt.Horizontal, "编号")
        self.queryModel.setHeaderData(1, Qt.Horizontal, "姓名")
        self.queryModel.setHeaderData(2, Qt.Horizontal, "性别")
        self.queryModel.setHeaderData(3, Qt.Horizontal, "年龄")
        self.queryModel.setHeaderData(4, Qt.Horizontal, "院系")

    # 得到记录数
    def getTotalRecordCount(self):
        self.queryModel.setQuery("select * from student")
        rowCount = self.queryModel.rowCount()
        print('rowCount=' + str(rowCount))
        return rowCount

    # 得到页数
    def getPageCount(self):
        if self.totalRecrodCount % self.PageRecordCount == 0:
            return (self.totalRecrodCount / self.PageRecordCount)
        else:
            return (self.totalRecrodCount / self.PageRecordCount + 1)

    # 记录查询
    def recordQuery(self, limitIndex):
        szQuery = ("select * from student limit %d,%d" % (limitIndex, self.PageRecordCount))
        print('query sql=' + szQuery)
        self.queryModel.setQuery(szQuery)

    # 刷新状态
    def updateStatus(self):
        szCurrentText = ("当前第%d页" % self.currentPage)
        self.currentPageLabel.setText(szCurrentText)

        # 设置按钮是否可用
        if self.currentPage == 1:
            self.prevButton.setEnabled(False)
            self.nextButton.setEnabled(True)
        elif self.currentPage == self.totalPage:
            self.prevButton.setEnabled(True)
            self.nextButton.setEnabled(False)
        else:
            self.prevButton.setEnabled(True)
            self.nextButton.setEnabled(True)

    # 设置总数页文本
    def setTotalPageLabel(self):
        szPageCountText = ("总共%d页" % self.totalPage)
        self.totalPageLabel.setText(szPageCountText)

    # 设置总记录数
    def setTotalRecordLabel(self):
        szTotalRecordText = ("共%d条" % self.totalRecrodCount)
        print('*** setTotalRecordLabel szTotalRecordText=' + szTotalRecordText)
        self.totalRecordLabel.setText(szTotalRecordText)

    # 前一页按钮按下
    def onPrevButtonClick(self):
        print('*** onPrevButtonClick ');
        limitIndex = (self.currentPage - 2) * self.PageRecordCount
        self.recordQuery(limitIndex)
        self.currentPage -= 1
        self.updateStatus()

    # 后一页按钮按下
    def onNextButtonClick(self):
        print('*** onNextButtonClick ');
        limitIndex = self.currentPage * self.PageRecordCount
        self.recordQuery(limitIndex)
        self.currentPage += 1
        self.updateStatus()

    # 转到页按钮按下
    def onSwitchPageButtonClick(self):
        # 得到输入字符串
        szText = self.switchPageLineEdit.text()


        # 得到页数
        pageIndex = int(szText)
        # 判断是否有指定页
        if pageIndex > self.totalPage or pageIndex < 1:
            QMessageBox.information(self, "提示", "没有指定的页面，请重新输入")
            return

        # 得到查询起始行号
        limitIndex = (pageIndex - 1) * self.PageRecordCount

        # 记录查询
        self.recordQuery(limitIndex);
        # 设置当前页
        self.currentPage = pageIndex
        # 刷新状态
        self.updateStatus();


if __name__ == '__main__':
    app = QApplication(sys.argv)
    # 创建窗口
    example = DataGrid()
    # 显示窗口
    example.show()
    sys.exit(app.exec_())

operation result:

Try it yourself