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 ('胡聰聰', 18, '男', '哈哈哈，哈哈哈')
-- 如果省略列名，那么必須要和字段一一對(duì)應(yīng)
INSERT INTO user VALUES (null, '胡聰聰', 18, '男', '哈哈哈，哈哈哈')
?
INSERT INTO user SET name='hcc', age=18, gender='男', content='嘻嘻嘻'

// 修改所有的數(shù)據(jù)
UPDATE USER SET name='胡西西'
// 根據(jù)條件修改
UPDATE USER set name='胡聰聰', content="這是內(nèi)容" WHERE id = 2

// 刪除所有的數(shù)據(jù)
DELETE FROM USER
?
// 刪除id為5的數(shù)據(jù)
DELETE FROM USER WHERE id = 5

-- 查詢所有數(shù)據(jù)
SELECT * FROM user
?
-- 查詢指定列
SELECT id, name,age from user

--- 并且
SELECT * from user where name='胡聰聰' AND age=21
?
--- 或者
SELECT * from user where name='胡聰聰' or age=21
?
-- 范圍查詢
?
-- 模糊查詢 ?%表示通配 ?_表示單個(gè)字符
SELECT * from user where name LIKE '胡%'
?
-- in語句
SELECT * from user where name in ('胡聰聰', 'hcc')
?
-- order by
-- 排序需要寫在最后面，，asc升序 ?desc：降序
SELECT * from user ORDER BY id desc
?
-- limit分頁
SELECT * from user ORDER BY id desc limit 3
SELECT * from user ORDER BY id desc limit 3,3
?
?
-- 獲取總條數(shù)
SELECT count(*) as total FROM user

npm install mysql

// 導(dǎo)入第三方包
const mysql = require('mysql')
// 創(chuàng)建連接
var connection = mysql.createConnection({
? // 本地
? host: 'localhost',
? user: 'root',
? password: 'root',
? // 數(shù)據(jù)庫名稱
? database: 'mydb',
? port: 3306
})
?
// 連接數(shù)據(jù)庫
connection.connect()
?
// 執(zhí)行sql語句
connection.query('select * from user where id = 8', (err, result) => {
? if (err) return console.log('查詢失敗', err)
? // result返回的是數(shù)組， 數(shù)組中是一個(gè)對(duì)象
? console.log(result)
})
?
// 關(guān)閉連接
connection.end()

var name = '胡聰聰'
// 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('錯(cuò)誤了', 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('錯(cuò)誤', 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('錯(cuò)誤', 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('錯(cuò)誤', err)
? ? console.log('添加成功了', result)
? }
)

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

// 導(dǎo)入mysql
const mysql = require('mysql')
?
// 創(chuàng)建連接對(duì)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()
}