用python语言编写一个新冠物资管理系统，要求至少包含20种功能，界面设计简洁，源代码

由于篇幅限制，无法在此处提供完整的源代码。以下是一个简单的示例，其中包含物资入库、出库、库存管理和物资查询等功能的代码：

import tkinter as tk
import sqlite3

# 连接到数据库
conn = sqlite3.connect('covid19.db')
c = conn.cursor()

# 创建物资表
c.execute('''CREATE TABLE IF NOT EXISTS materials
             (id INTEGER PRIMARY KEY,
              name TEXT,
              amount INTEGER,
              price REAL)''')

# 定义主界面
class MainFrame(tk.Frame):
    def __init__(self, master=None):
        super().__init__(master)
        self.master = master
        self.pack()
        self.create_widgets()

    def create_widgets(self):
        # 物资入库
        self.add_material_label = tk.Label(self, text="物资入库")
        self.add_material_label.pack()
        
        self.name_label = tk.Label(self, text="物资名称")
        self.name_label.pack()
        self.name_entry = tk.Entry(self)
        self.name_entry.pack()

        self.amount_label = tk.Label(self, text="数量")
        self.amount_label.pack()
        self.amount_entry = tk.Entry(self)
        self.amount_entry.pack()

        self.price_label = tk.Label(self, text="价格")
        self.price_label.pack()
        self.price_entry = tk.Entry(self)
        self.price_entry.pack()

        self.add_material_button = tk.Button(self, text="入库", command=self.add_material)
        self.add_material_button.pack()

        # 物资出库
        self.remove_material_label = tk.Label(self, text="物资出库")
        self.remove_material_label.pack()
        
        self.name_remove_label = tk.Label(self, text="物资名称")
        self.name_remove_label.pack()
        self.name_remove_entry = tk.Entry(self)
        self.name_remove_entry.pack()

        self.amount_remove_label = tk.Label(self, text="数量")
        self.amount_remove_label.pack()
        self.amount_remove_entry = tk.Entry(self)
        self.amount_remove_entry.pack()

        self.remove_material_button = tk.Button(self, text="出库", command=self.remove_material)
        self.remove_material_button.pack()

        # 物资库存管理
        self.materials_label = tk.Label(self, text="物资库存管理")
        self.materials_label.pack()

        self.materials_listbox = tk.Listbox(self)
        self.materials_listbox.pack()

        self.refresh_button = tk.Button(self, text="刷新", command=self.refresh_materials)
        self.refresh_button.pack()

        # 物资查询
        self.query_material_label = tk.Label(self, text="物资查询")
        self.query_material_label.pack()

        self.name_query_label = tk.Label(self, text="物资名称")
        self.name_query_label.pack()
        self.name_query_entry = tk.Entry(self)
        self.name_query_entry.pack()

        self.query_material_button = tk.Button(self, text="查询", command=self.query_material)
        self.query_material_button.pack()

    # 添加物资
    def add_material(self):
        name = self.name_entry.get()
        amount = int(self.amount_entry.get())
        price = float(self.price_entry.get())
        c.execute("INSERT INTO materials (name, amount, price) VALUES (?, ?, ?)", (name, amount, price))
        conn.commit()

    # 出库物资
    def remove_material(self):
        name = self.name_remove_entry.get()
        amount = int(self.amount_remove_entry.get())
        c.execute("SELECT amount FROM materials WHERE name=?", (name,))
        current_amount = c.fetchone()[0]
        if current_amount < amount:
            tk.messagebox.showerror("出库失败", "库存不足")
        else:
            new_amount = current_amount - amount
            c.execute("UPDATE materials SET amount=? WHERE name=?", (new_amount, name))
            conn.commit()

    # 刷新物资列表
    def refresh_materials(self):
        self.materials_listbox.delete(0, tk.END)
        c.execute("SELECT * FROM materials")
        for row in c.fetchall():
            self.materials_listbox.insert(tk.END, f"{row[1]}：{row[2]}个，单价：{row[3]}元")

    # 查询物资
    def query_material(self):
        name = self.name_query_entry.get()
        c.execute("SELECT * FROM materials WHERE name=?", (name,))
        row = c.fetchone()
        if row:
            tk.messagebox.showinfo("物资信息", f"{row[1]}：{row[2]}个，单价：{row[3]}元")
        else:
            tk.messagebox.showerror("物资不存在", "未找到相关物资")

# 运行主程序
root = tk.Tk()
app = MainFrame(master=root)
app.mainloop()

# 关闭数据库连接
conn.close()

这只是一个简单的示例，您可能需要根据具体需求进行更改和扩展。