nodejs（11）Express 中进行数据库操作

// 1.导入操作数据库的包
const mysql = require(‘mysql‘)

// 2.创建数据库对象
const conn = mysql.createConnection({
  host:‘127.0.0.1‘,
  user: ‘root‘,
  password: ‘root‘,
  database: ‘heima47‘
})

// CRUD
// -------- 查询数据 ----------
conn.query(‘要执行的Sql语句‘)

const sql1 = ‘select * from users‘
conn.query(sql1, (err, result) => {
  if(err) return console.log(err.message)
  console.log(result)
})

// 1.导入操作数据库的包
const mysql = require(‘mysql‘)

// 2.创建数据库对象
const conn = mysql.createConnection({
  host:‘127.0.0.1‘,
  user: ‘root‘,
  password: ‘root‘,
  database: ‘heima47‘
})

// CRUD
// -------- 添加数据 ----------
const user = {username: ‘宝贝1‘, address: ‘美国‘}
const sql2 = ‘insert into users(username, address) values ("‘ + user.username + ‘","‘ + user.address + ‘")‘
conn.query(sql2, (err, result) => {
  if(err) return console.log(err.message)
  console.log(result)
})

/* const user = {username: ‘欧松‘, address: ‘唐山‘}
const sql2 = ‘insert into users set ?‘
conn.query(sql2, user, (err, result) => {
  if(err) return console.log(err.message)
  console.log(result)
})
 */

// 1.导入操作数据库的包
const mysql = require(‘mysql‘)

// 2.创建数据库对象
const conn = mysql.createConnection({
  host:‘127.0.0.1‘,
  user: ‘root‘,
  password: ‘root‘,
  database: ‘heima47‘
})

// CRUD
// -------- 修改数据 ----------
// conn.query(‘要执行的Sql语句‘)
const user = {id: 13, username: ‘美丽‘, address: ‘济南‘}
const sql3 = ‘update users set ? where id=?‘
conn.query(sql3, [user, user.id], (err, result) => {
  if(err) return console.log(err.message)
  console.log(result)
})

// 1.导入操作数据库的包
const mysql = require(‘mysql‘)

// 2.创建数据库对象
const conn = mysql.createConnection({
  host:‘127.0.0.1‘,
  user: ‘root‘,
  password: ‘root‘,
  database: ‘heima47‘
})

// CRUD
// -------- 删除数据 ----------
// conn.query(‘要执行的Sql语句‘)
const sql4 = ‘delete from users where id=?‘
conn.query(sql4, 6, (err, result) => {
  if(err) return console.log(err.message)
  console.log(result)
})