我不明白为什么我不能在数据库中的现有表中放置值;

问：

我在数据库中有一个预先创建的表，我想从前端（即由用户）插入值，但由于某种原因，我编写的代码无法实现我所寻求的：/

我仍然是一个初学者，所以对我苛刻，这样我就可以通过记住我在这里遇到的情况来学习。

下面是代码的服务器端：

const express = require("express");
const app = express();
const cors = require("cors");
const pool = require("./db");
const bodyParser = require("body-parser");

app.use(bodyParser.json());
app.use(cors());
app.use(express.json());

// input values
app.put("/admin/staff", async (req, res) => {
    try {
        const {adminstration} = await req.body;
        // contains the admin table details to be added
        const newadminstration = await pool.query("INSERT INTO adminstration (adminstration) VALUES ($1) RETURNING *", [adminstration]);
        res.json(newadminstration.rows[0]);
        console.log(newadminstration)
    } catch (err) {
        console.error(err.message);
    }
});
app.listen(5000, () => {
    console.log("server is running on port 5000")
});

下面是代码的前端端：

import React from 'react';
import { useState } from 'react';
import Box from '@mui/material/Box';
import TextField from '@mui/material/TextField';
import {  Input} from '@mui/material';

export default function Adminfun() { 
    const [adminstration, setadminstration] = useState({admin_name:"", admin_email:"", admin_password:""});
const bbb= async (e) => {
        e.preventdefault();
        try {

            const body = { adminstration };
            const response = await fetch("http://localhost:5000/admin/staff", {
                method: "PUT",
                headers: {"Content-Type": "application/json"},
                body: JSON.stringify(body)
            });
            console.log(response)
        } catch (err) {
            console.error(err.message)
        } 
    }; return (
    <Box
    component="form"
    sx={{
      '& > :not(style)': { m: 1, width: '25ch' },
    }}
    noValidate
    autoComplete="off">
        <TextField id="outlined-basic" label="Name" variant="outlined" value={adminstration.admin_name} 
        onChange={(Event) => 
            {const newAdminstration = {...adminstration};
            newAdminstration.admin_name = Event.target.value;
            setadminstration(newAdminstration)}}/>
             {/* {setadminstration({...adminstration, admin_name: Event.target.value})}}/> */}
        <TextField id="filled-basic" label="Email" variant="filled" value={adminstration.admin_email} 
        onChange={(Event) =>
           {setadminstration({...adminstration, admin_email: Event.target.value})}}/>
        <TextField id="standard-basic" label="Password" variant="standard" value={adminstration.admin_password} 
        onChange={(Event) => 
            {const newAdminstration = {...adminstration};
            newAdminstration.admin_password = Event.target.value;
            setadminstration(newAdminstration)}}/>
    <br></br>
    <Input type='submit' onSubmit={bbb} >Submit</Input>
   </Box>)
};

后端的 Node JS，PostgreSQL 数据库，前端的 React。