def query_employee(self, id): conn = pymysql.connect(host='39.99.214.172', user='root', password='Solotion.123', database='jj_tset') cursor = conn.cursor() cursor.execute("SELECT * FROM employee_table WHERE user_id='%s'" % id) result = cursor.fetchone() conn.close() return result # 读取数据 def read_data(self): data = self.ser.readline() if data: # 解析数据 id = data.decode().strip() # 查询员工信息 result = self.query_employee(id) if result: # 更新UI界面 self.id_label.setText("员工ID：" + result[0]) self.name_label.setText("姓名：" + str(result[1])) self.six_label.setText("性别：" + result[2]) self.sfz_label.setText("身份证：" + str(result[3])) self.tel_label.setText("电话：" + result[4]) else: # 显示空白信息 self.id_label.setText("员工ID：") self.name_label.setText("姓名：") self.six_label.setText("性别：") self.sfz_label.setText("身份证：") self.tel_label.setText("电话：") # 定时读取数据 QTimer.singleShot(100, self.read_data) def closeEvent(self, event): # 关闭串口 self.ser.close()怎么改为多线程来优化程序性能，将耗时的操作放在子线程中执行，避免阻塞主线程

可以使用Python中的`QThread`来实现多线程功能，将`read_data`函数中的查询数据库操作放在子线程中执行，避免阻塞主线程。示例代码如下：

from PyQt5.QtCore import QThread, QTimer, pyqtSignal

class QueryThread(QThread):
    query_result = pyqtSignal(object)

    def __init__(self, id):
        super().__init__()
        self.id = id

    def run(self):
        conn = pymysql.connect(host='39.99.214.172', user='root', password='Solotion.123', database='jj_tset')
        cursor = conn.cursor()
        cursor.execute("SELECT * FROM employee_table WHERE user_id='%s'" % self.id)
        result = cursor.fetchone()
        conn.close()
        self.query_result.emit(result)  # 发送查询结果信号

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self.query_thread = None  # 查询线程

    def read_data(self):
        data = self.ser.readline()
        if data:
            id = data.decode().strip()
            if not self.query_thread:  # 如果查询线程不存在，则创建并启动
                self.query_thread = QueryThread(id)
                self.query_thread.query_result.connect(self.update_ui)
                self.query_thread.start()
            else:
                self.query_thread.id = id  # 如果查询线程已存在，则更新查询ID

        QTimer.singleShot(100, self.read_data)

    def update_ui(self, result):
        if result:
            self.id_label.setText("员工ID：" + result[0])
            self.name_label.setText("姓名：" + str(result[1]))
            self.six_label.setText("性别：" + result[2])
            self.sfz_label.setText("身份证：" + str(result[3]))
            self.tel_label.setText("电话：" + result[4])
        else:
            self.id_label.setText("员工ID：")
            self.name_label.setText("姓名：")
            self.six_label.setText("性别：")
            self.sfz_label.setText("身份证：")
            self.tel_label.setText("电话：")

    def closeEvent(self, event):
        self.ser.close()
        if self.query_thread:
            self.query_thread.quit()
            self.query_thread.wait()