建庫，選擇庫 create database pygodnet; use pygodnet;

刪庫 drop database pygodnet;

建表，刪表 create table user(userid int(11),username varchar(32),password char(32)); drop table user;

改表名 alter table user rename users;

表字段改名 alter table user change userid id int(11);

修改欄位型別與位置 alter table user modify username char(32) first;

新增刪除表字段 alter table user add column password char(64) after username; alter table user drop column sex;

create建立索引，create 不能建立主鍵索引，注意與alter的區別 create index in_id on t1(id);

alter建立索引，create 不能建立主鍵索引，注意與alter的區別 alter table users add unique(欄位名 ); #fulltext(欄位名 );primary key(欄位名 );index(欄位名)

刪除索引 alter table users drop index username on t1;

刪除主鍵索引，先取消遞增 alter table users modify id int(11) unsigned not null; alter table users drop primary key;

插入資料方法一，所有欄位，順序一致 insert into users values(1,“haha”,“adfdsfadsf12”),(2,“xixi”,“afdsf123321”);

插入資料方法二，設定了遞增的欄位可不操作 insert into users(id,username,password) values(3,“hehe”,“12333adf123”);

替換列資料 update scores set nu=replace(nu,1,2);

去重 select distinct balance from money;

排序，desc降序，asc升序。 select * from money where age>30 order by balance desc,age asc limit 2 ,5; asc升序；

分組，group by select count(province),province from money group by province;

條件篩選group by select count(province) as result,province from money group by province with rollup;

條件篩選group by select count(province) as result,province from money group by province having result>1;

表聯合查詢 select user.username as ‘使用者名稱’,order_goods.oid,order_goods.name as “商品名” from user,order_goods where user.uid=order_goods.uid;

表聯合查詢2 select user.username as ‘使用者’,order_goods.name as “商品” from user inner join order_goods on user.uid=order_goods.uid;

left join 語法 select * from user left join order_goods on user.uid=order_goods.uid;

查詢 select * from user where uid in(select uid from order_goods); select uid from user union all select uid from order_goods;

更新資料update update user set username=“哈哈”,password=“123456” where uid=8;

同時對兩個表更新 update money m,users u set m.balance=m.balance*u.id,u.password=m.balance where m.id=u.id;

delete from，累加id從原來的基礎上累加，如1，2，3，將id=2刪除了,id=3不變！ delete from money where id>9; delete from 表名；

truncate清空表以後 id 從1 開始 truncate table users;

資料庫遠端連線,注意符號的使用 grant 許可權 on 庫名.表名 to ‘使用者名稱’@‘ip地址’ identified by 密碼； grant all on . to ‘root’@‘localhost’ identified by ‘123456’ with grant option; grant select,insert on class1824. to ‘jinxingping’@‘localhost’ identified by ‘123321’; flush privileges; service mysql restart；

刪除指定許可權 revoke insert on class1824.* from ‘jinxingping’@‘localhost’;

複製表結構和資料 create table user1 like users； insert into user1 select * from users；

表檢視 view create view v_t1 as select * from t1 where id>2 and id<8; show create/drop view v_t1;

mysql常用內建函式： mysql 顯示內容 用 select 字串函式 mysql> select concat(“hello”,“world”) as nihao; #拼接字串 select lcase(“MYSQL”);#轉小寫 select ucase(“mysql”); #轉大寫 mysql> select length(“haha”); 字串的長度 mysql> select ltrim(" haha"); 去除左側空格 ±------------------+ | ltrim(" haha") | ±------------------+ | haha | ±------------------+ 1 row in set (0.00 sec)

mysql> select rtrim(" haha ");去除右側空格 mysql> select repeat(“重要的事情說三遍”,6); select replace(“java 是世界上最好的語言”,“java”,“python”); mysql> select substr(“python is so good”,2,7); 從第二個字元開始 擷取7個 mysql 從1開始 mysql> select concat(space(20),‘haha’); #生成20個空格 數學函式 mysql> select ceiling(123.1); mysql> select floor(123.1); mysql> select rand(); 求隨機數 0-1之間的小數 mysql> select bin(10);

日期函式 mysql> select curdate(); 返回日期 2018-7-25 mysql> select curtime(); 11:21:33 mysql> select now(); 日期+時間 2018-07-25 11:22:14 mysql> select week(now()); 返回29 表示當前第幾周 mysql> select year(now()); 返回2018 mysql> select unix_timestamp(now()); 當前時間的時間戳 mysql> select from_unixtime(1532489069); ±--------------------------+ | from_unixtime(1532489069) | ±--------------------------+ | 2018-07-25 11:24:29 | ±--------------------------+ 將當前的時間戳格式化為日期

轉載自https://blog.csdn.net/pygodnet/article/details/82810885?tdsourcetag=s_pcqq_aiomsg