nodejs中关于mysql数据库的操作

CREATE TABLE user(
    id INT auto_increment PRIMARY KEY,
    name VARCHAR(255) NOT NULL,
    age INT ,
    gender VARCHAR(4),
    content VARCHAR(255)
)

INSERT INTO user (name, age, gender, content) VALUES ('胡聪聪', 18, '男', '哈哈哈，哈哈哈')
-- 如果省略列名，那么必须要和字段一一对应
INSERT INTO user VALUES (null, '胡聪聪', 18, '男', '哈哈哈，哈哈哈')
 
INSERT INTO user SET name='hcc', age=18, gender='男', content='嘻嘻嘻'

// 修改所有的数据
UPDATE USER SET name='胡西西'
// 根据条件修改
UPDATE USER set name='胡聪聪', content="这是内容" WHERE id = 2

// 删除所有的数据
DELETE FROM USER
 
// 删除id为5的数据
DELETE FROM USER WHERE id = 5

-- 查询所有数据
SELECT * FROM user
 
-- 查询指定列
SELECT id, name,age from user

--- 并且
SELECT * from user where name='胡聪聪' AND age=21
 
--- 或者
SELECT * from user where name='胡聪聪' or age=21
 
-- 范围查询
 
-- 模糊查询  %表示通配  _表示单个字符
SELECT * from user where name LIKE '胡%'
 
-- in语句
SELECT * from user where name in ('胡聪聪', 'hcc')
 
-- order by
-- 排序需要写在最后面，，asc升序  desc：降序
SELECT * from user ORDER BY id desc
 
-- limit分页
SELECT * from user ORDER BY id desc limit 3
SELECT * from user ORDER BY id desc limit 3,3
 
 
-- 获取总条数
SELECT count(*) as total FROM user

npm install mysql

// 导入第三方包
const mysql = require('mysql')
// 创建连接
var connection = mysql.createConnection({
  // 本地
  host: 'localhost',
  user: 'root',
  password: 'root',
  // 数据库名称
  database: 'mydb',
  port: 3306
})
 
// 连接数据库
connection.connect()
 
// 执行sql语句
connection.query('select * from user where id = 8', (err, result) => {
  if (err) return console.log('查询失败', err)
  // result返回的是数组， 数组中是一个对象
  console.log(result)
})
 
// 关闭连接
connection.end()

var name = '胡聪聪'
// 使用?表示占位，可以防止sql注入
connect.query(`select * from user where name=?`, name, (err, result) => {
  if (err) return console.log('错误了', err)
  console.log(result)
})

connect.query(
  'insert into user (name, age, gender, content) values (?, ?, ?, ?)',
  ['胡嘻嘻', 18, '男', '哈哈哈哈'],
  err => {
    if (err) return console.log('错误', err)
    console.log('添加成功了')
  }
)
 
// 方式2
connect.query(
  'insert into user set ?',
  {
    name: '胡洗洗',
    age: 30,
    gender: '男',
    content: '哈哈哈'
  },
  (err, result) => {
    if (err) return console.log('错误', err)
    console.log('添加成功了', result)
  }
)

connect.query(
  'update user set ? where id = ?',
  [
    {
      name: '胡洗洗',
      age: 30,
      gender: '男',
      content: '哈哈哈'
    },
    10
  ],
  (err, result) => {
    if (err) return console.log('错误', err)
    console.log('添加成功了', result)
  }
)

connect.query('delete from user where id = ?', [10], (err, result) => {
  if (err) return console.log('失败', err)
  console.log(result)
})

// 导入mysql
const mysql = require('mysql')
 
// 创建连接对象
const connect = mysql.createConnection({
  host: 'localhost',
  port: 3306,
  user: 'root',
  password: 'root',
  database: 'mydb'
})
 
exports.query = function(sql, params, callback) {
  connect.connect()
  connect.query(sql, params, (err, data) => {
    callback &&  callback(err, data)
  })
  connect.end()
}