代码示例，使用Element,Koa,SQLyog创建用户管理的页面，用户信息包括姓名，电话，邮箱，地址，可以对用户进行增，删，改，查操作

好的，根据您的要求，以下是一个使用Element,Koa,SQLyog创建用户管理页面的代码示例：

前端页面代码（使用Element实现）：

<template>
  <div>
    <el-table :data="userData" border>
      <el-table-column label="姓名" prop="name"></el-table-column>
      <el-table-column label="电话" prop="phone"></el-table-column>
      <el-table-column label="邮箱" prop="email"></el-table-column>
      <el-table-column label="地址" prop="address"></el-table-column>
      <el-table-column>
        <template slot-scope="scope">
          <el-button type="primary" @click="editUser(scope.$index, scope.row)">编辑</el-button>
          <el-button type="danger" @click="removeUser(scope.$index, scope.row)">删除</el-button>
        </template>
      </el-table-column>
    </el-table>
    <el-dialog :visible.sync="dialogVisible" title="添加/编辑用户信息">
      <el-form :model="userForm">
        <el-form-item label="姓名" :label-width="formLabelWidth">
          <el-input v-model="userForm.name" autocomplete="off"></el-input>
        </el-form-item>
        <el-form-item label="电话" :label-width="formLabelWidth">
          <el-input v-model="userForm.phone" autocomplete="off"></el-input>
        </el-form-item>
        <el-form-item label="邮箱" :label-width="formLabelWidth">
          <el-input v-model="userForm.email" autocomplete="off"></el-input>
        </el-form-item>
        <el-form-item label="地址" :label-width="formLabelWidth">
          <el-input v-model="userForm.address" autocomplete="off"></el-input>
        </el-form-item>
      </el-form>
      <div slot="footer">
        <el-button @click="dialogVisible = false">取消</el-button>
        <el-button type="primary" @click="saveUser">保存</el-button>
      </div>
    </el-dialog>
    <el-button type="primary" @click="addUser">添加用户</el-button>
  </div>
</template>

<script>
import axios from 'axios';

export default {
  data() {
    return {
      userData: [],        // 用户数据
      userForm: {},        // 用户表单
      dialogVisible: false, // 弹窗可见
      formLabelWidth: '80px', // 表单标签宽度
    }
  },
  mounted() {
    this.getUserData();   // 加载用户数据
  },
  methods: {
    // 获取用户数据
    getUserData() {
      axios.get('/api/user')
        .then(res => {
          this.userData = res.data.data;
        })
        .catch(err => {
          console.log(err);
        });
    },
    // 打开添加用户弹窗
    addUser() {
      this.userForm = {};
      this.dialogVisible = true;
    },
    // 打开编辑用户弹窗
    editUser(index, row) {
      this.userForm = Object.assign({}, row);
      this.dialogVisible = true;
    },
    // 保存用户信息
    saveUser() {
      axios.post('/api/user', this.userForm)
        .then(res => {
          this.dialogVisible = false;
          this.getUserData();
        })
        .catch(err => {
          console.log(err);
        });
    },
    // 删除用户信息
    removeUser(index, row) {
      axios.delete(`/api/user/${row.id}`)
        .then(res => {
          this.getUserData();
        })
        .catch(err => {
          console.log(err);
        });
    },
  }
};
</script>

后端代码（使用Koa和SQLyog实现）：

const Koa = require('koa');
const Router = require('koa-router');
const bodyParser = require('koa-bodyparser');
const mysql = require('mysql');
const cors = require('@koa/cors');

const app = new Koa();
const router = new Router();
const connection = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: '',
  database: 'user',
});

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

// 获取用户列表
router.get('/api/user', async ctx => {
  try {
    const results = await new Promise((resolve, reject) => {
      connection.query('SELECT * FROM user', (err, results) => {
        if (err) {
          reject(err);
        } else {
          resolve(results);
        }
      });
    });
    ctx.body = {
      code: 0,
      msg: 'success',
      data: results,
    }
  } catch (err) {
    ctx.body = {
      code: -1,
      msg: 'error',
      data: err.message,
    }
  }
});

// 添加/编辑用户
router.post('/api/user', async ctx => {
  const user = ctx.request.body;
  const sql = user.id
    ? `UPDATE user SET name='${user.name}', phone='${user.phone}', email='${user.email}', address='${user.address}' WHERE id=${user.id}`
    : `INSERT INTO user (name, phone, email, address) VALUES ('${user.name}', '${user.phone}', '${user.email}', '${user.address}')`;
  try {
    await new Promise((resolve, reject) => {
      connection.query(sql, (err, results) => {
        if (err) {
          reject(err);
        } else {
          resolve(results);
        }
      });
    });
    ctx.body = {
      code: 0,
      msg: 'success',
    }
  } catch (err) {
    ctx.body = {
      code: -1,
      msg: 'error',
      data: err.message,
    }
  }
});

// 删除用户
router.delete('/api/user/:id', async ctx => {
  const id = ctx.params.id;
  try {
    await new Promise((resolve, reject) => {
      connection.query(`DELETE FROM user WHERE id=${id}`, (err, results) => {
        if (err) {
          reject(err);
        } else {
          resolve(results);
        }
      });
    });
    ctx.body = {
      code: 0,
      msg: 'success',
    }
  } catch (err) {
    ctx.body = {
      code: -1,
      msg: 'error',
      data: err.message,
    }
  }
});

app.use(router.routes());
app.use(router.allowedMethods());

app.listen(3000, () => {
  console.log('server is running at http://localhost:3000');
});

注意，以上代码示例为简化版，可能需要您根据实际情况进行修改。另外，此代码示例仅供参考，不保证完全正确、合法和可用。