SQL2
1、DML(data manipulation language)
- INSERT INTO 表名 VALUES活动板房 (值1,值2,值3…值n); --完整插入
- INSERT INTO 表名(列名,列名) VALUES (值1,值2); ---部分插入
- 更新数据UPDAT阿泰宁E
- UPDAT具备是什么意思E 表名 SET 列名=值 WHERE CONDITION磁盘清理; --- 语法
-
update t6 set name关闭qq空间申请='cc' where id=2;
-
update mysql活动主题.user set authentication_string=password("QianF磁盘分区eng@123456") where usIPer="root"; -- 更改数据库密码
- flush privileg163网易免费邮箱es -- 更新数据库
- 删除数据DELETE
-
DELETE FROM 表名 WHERE CONDITION; --- 语法
- delete from t6 where id=2;
- 更改表的结构
-
alter table t2 add xingbie enum('nan','nv'); --- 增加列
- 增加列:alter table t2 drop xingbie ; --- 减少列
2、DQL语句 数据库查询语言
(1)目的
在MySQL管理软件中,可具备使用警犬追踪或者鉴别条件的以通过SQL语句中的DQL语言来实现数据的
(2)MySQL查询
- 准备环境
-
CREATE16 TABLE company.employee5(
id int primary ke二进制转八进制y AUTO_INC关闭花呗REMENT not163邮箱登录入口 null,
name varchar(30) not null,
se是什么样的年纪太多忧愁是什么歌x enum('male','female') default 'male' not null,
hire_date date not null,
post varchar(50) not null,
job_description varchar(100),
salary double(15,2) not null,
office int,
dep_id int
); ---- 结构语句 -
desc employee5; --- 查看表结构
- insert into c具备的反义词ompany.employee5(name,s活动房ex,hire_date,post,job_descripti阿塔兰忒on,salary,office,dep_id) values
('jack','male','20180202','instructor','teach',5000,5data01,100),
('tom','male','20180203','instructor','teach',5500,501,100),
('robin'魔临,'male','20180202','instructor','teach',8000,501,100),
('alice','female',大唐开局震惊了李世民'20180202','instructor','teach',7200,501,100),
('aofa','male','20180202','hr','hr是什么表情cc'牡蛎,600,502,101),
('harry','male'163.免费邮箱,'20180202','hr',NULL,6000,502,101),
('emma16','femal是什么意思日语e','201磁盘阵列80206','sale','sale信息管理与信息系统cc',20000,503,102),
('christine163.免费邮箱','female','20180205','sale','sa大唐开局震惊了李世民lecc',2200,503,102),
('zhuzhu','male','20180205','sale',N阿陶陶的三部小说是ULL,2200,503,102),
('gougou','m是什么样的年纪太多忧愁是什么歌ale','20180205计算器在线','sale','',2200,5大明流匪03,102); ----插入数据
- 简单查询
- SELECT * FROM 表名; --- 查看所有列
- SELECT 列1,列2,列3 FROM 表名; --- 查看部分列
- SELECT name, salary, salary*14 FROM employee5; --- 查看年薪
- SELECT name, salary, salary*14 as 年薪 FROM employee5; ---查看个性化的年薪
- 条活动方案格式模板件查询
-
单条件查询where
SELECT具备造句 name,post FROM employee5 WHERE post='hr';
-
多条件查询AND/OR
SELECT name,salary FROM employee5 WHERE post='hr' AND salary>1000;
SELECT name, salary FROM employee5 WHERE salary=6000 OR salary=8000
-
关键字BETWEEN AND 在什么之间
SELECT name,salary FROM em163.免费邮箱ployee5 WHERE salary BETWEEN 5000 AND 15000;
SELECT name,具备造句sa具备和俱备lary FROM employee5 WHERE salary NOT BETWEEN 5000 AND 15000;
-
关键字IN集合查询
SELECT name, salary FROM employee5 WHERE salary IN (4000,5000,6000,9000) ;
SELECT name, salary FROM employee WHERE sipoalary NO二进制转十进制计算器T IN (4000,5000,6000,9000) ;是什么样的年纪太多忧愁是什么歌
-
关键字IS NULL
SELECT name,job_description FROM employee5 W163邮箱HERE job_descri计算器ption IS NULL139;
SELECT name,job_des活动cription FROM employee5 WHERE job_description='';大唐开局震惊了李世民 --错误示范
-
关键字LIKE模糊查询
SELECT FR信息素OM employee5 WHERE name LIKE 'al%'; //通配符’%’代表多个任意字符,注意不是she活动ll的""星号。mysql使用"%" ---模糊查找‘姓a’
SELECT * FROM employee5 WHERE name LIKE 'al___'; // 注意不是shell的“?”问号。mys磁盘清理ql使用下划线 -
- 查询排序
-
升序排列
SELECT * FROM 表名 ORDER BY 工资的列名 ASC;
-
降序排列
SELECT * FROM 表名 ORDER BY 工资的列名 DESC;
-
查询前几位
SELECT * FROM employee5 ORDER BY salary DESC LIMIT 5; //默认初始位置为0
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