如何只删除或编辑sql表中的一行？

Question

that is my app and I used search button to edit information easily 我在 python 中使用该代码向本地数据库添加、删除、更新信息......它在添加信息时运行良好，但是当我使用更新时，数据库中的所有信息或行变得相同。另外，当删除所有数据时，可能是因为使用一个搜索栏来编辑或删除添加的数据

这是我的代码：

import sys
import os
import time

from PyQt5 import QtCore, QtGui, QtWidgets, uic
import mysql.connector
from mysql.connector import errorcode

FORM_CLASS, _ = uic.loadUiType(os.path.join(os.path.dirname(__file__),"mahmoudtarek.ui"))

class Main(QtWidgets.QMainWindow, FORM_CLASS):
    def __init__(self,parent=None):
        super(Main,self).__init__(parent)
        self.setupUi(self)
        self.InitUI()
        self.conn = None

        self.handle_buttons()
        self.handle_db_connections()

    def InitUI(self):
        ## changes in the run time
        pass

    def handle_buttons(self):
          ## all buttons in the app
        self.pushButton.clicked.connect(self.add_mahmoud_friends)
        self.pushButton_3.clicked.connect(self.update_mahmoud_friends)
        self.pushButton_2.clicked.connect(self.delete_mahmoud_friends)
        self.pushButton_6.clicked.connect(self.search_mahmoud_friends)


    def handle_db_connections(self):
        try:
            self.conn = mysql.connector.connect(
                host='127.0.0.1',
                database='mydb',
                user='root',
                password='134668691011',
                use_pure=True)  # use_pure is set to true

            if self.conn.is_connected():
                db_Info = self.conn.get_server_info()
                print("Connected to MySQL database using C extension... MySQL Server version on ", db_Info)
        except mysql.connector.Error as err:
            print("Error while connecting to MySQL using C extension", err)

    def add_mahmoud_friends(self):
        mth_friends = self.lineEdit.text()
        mth_search = self.lineEdit_4.text()
        if self.conn:
            c = self.conn.cursor()
            try:
                c.execute('''INSERT INTO ahmed (mth_friends,mth_search) values (%s,%s)''', (mth_friends,mth_search))
                self.conn.commit()
                self.lineEdit.setText('')
                self.lineEdit_4.setText('')
                self.statusBar.showMessage('ok mahmoud')


            except mysql.connector.Error as err:
                print("Error: ", err)

    def update_mahmoud_friends(self):
        mth_friends = self.lineEdit.text()
        mth_search = self.lineEdit_4.text()
        if self.conn:
            c = self.conn.cursor()
            try:
                c.execute('''UPDATE ahmed SET mth_friends = %s,mth_search = %s''', (mth_friends, mth_search))
                self.conn.commit()
                self.lineEdit.setText('')
                self.lineEdit_4.setText('')
                self.statusBar.showMessage('ok mahmoud')
                self.lineEdit_3.setText('')


            except mysql.connector.Error as err:
                print("Error: ", err)

    def delete_mahmoud_friends(self):
        c = self.conn.cursor()
        sql = '''DELETE FROM ahmed WHERE mth_search = %s'''
        mth_search = self.lineEdit_3.text()
        c.execute(sql, [(mth_search)])
        self.conn.commit()
        self.statusBar.showMessage("ok")
        self.lineEdit.setText('')
        self.lineEdit_4.setText('')
        self.lineEdit_3.setText('')


    def search_mahmoud_friends(self):
        if self.conn:
            c = self.conn.cursor()

            try:

                sql = '''SELECT * FROM ahmed WHERE mth_search = %s'''
                mth_search = self.lineEdit_3.text()
                c.execute(sql, [(mth_search)])
                data = c.fetchall()
                for row in data :
                    print(row)
                    self.lineEdit.setText(str(row[1]))
                    self.lineEdit_4.setText(str(row[2]))

            except mysql.connector.Error as err:
              print("Error: ", err)

    def closeEvent(self, event):
        if self.conn:
            self.conn.close()
        super(Main, self).closeEvent(event)


def main():
    app= QtWidgets.QApplication(sys.argv)
    window =Main()
    window.show()
    app.exec_()

if __name__ == '__main__':
    main()

我需要帮助，因为我还是个初学者。如果有人知道这个问题，请给我写正确的代码。由于我搜索太多......最后谢谢你

Answer 1

当你UPDATE时，你需要添加一个条件，否则表格中的每一行都会被这些值更新。

在您的代码中：

c.execute('''UPDATE ahmed SET mth_friends = %s,mth_search = %s''', (mth_friends, mth_search))

应该有一个条件，像这样：

c.execute('''UPDATE ahmed SET mth_friends = %s,mth_search = %s WHERE {ADD CONDITION HERE}''', (mth_friends, mth_search))

如果要更新或删除单个行，则希望条件匹配主键或唯一键列。使用涉及任何其他类型列的条件将更新或删除与该条件匹配的所有行。 （感谢Raymond Nijland）