MySQL常用DDL、DML、DCL语言整理

DDL

----Data Definition Language 数据库定义语言 如 create procedure之类

创建数据库

CREATE DATABASE [IF NOT EXISTS] DBNAME [CHARACTER SET 'CHAR_NAME'] [COLLATE 'COLL_NAME']

修改:ALTER 删除:DROP

DML

----Data Manipulation Language 数据操纵语言

如insert,delete,update,select(插入、删除、修改、检索)插入修改数据

mysql>INSERT INTO students (Name,Gender,teacher) VALUE ('lujunyi','M','mage'),('wusong','M','zhuima');

mysql>INSERT INTO students SET Name='lujunyi',Gender='M',tearcher='zhuima';

更新数据

mysql>UPDATE tb_name SET column=value WHERE column=value;

mysql>UPDATE students SET Course='mysql' WHERE Name='lujunyi';

替换数据：

和UPDATE使用方式一样,只要将UPDATE换成REPLACE即可

删除数据：

mysql>DELETE FROM tb_name WHERE conditions;

mysql>DELETE FROM students WHERE Course='mysql';

清空表：

mysql>TRUNCATE tb_name

查询数据

单表查询：

mysql>SELECT [DISTINCT] column FROM tb_name WHERE CONDITION;

EXAMPLE:

#基本投影查询

mysql>SELECT Name,teacher FROM students WHERE Name='wusong';

#重复的结果只显示一次

mysql>SELECT DISTINCT Gender FROM students;

#组合条件,可以使用AND,OR,NOT,XOR组合多个条件

mysql>SELECT * FROM students WHERE Age>20 AND Gender='M';

#使用BETWEEN...AND...筛选出年龄介于20-25之间的数据

mysql>SELECT * FROM students WHERE Age BETWEEN 20 AND 25;

#查询Name以Y开头的的数据，%表示任意长度的任意字符，_表示任意单个字符

mysql>SELECT * FROM student WHERE Name LIKE 'Y%';

#使用正则表达式匹配查询,关键词为RLINK或者REGEXP

mysql> SELECT * FROM students WHERE Name RLINK '^[MNY].*$';

#使用IN关键词，将条件限定在一个列表中。用IS关键词，表示条件是否为空（IS NULL 或者 IS NOT NULL）

mysql>SELECT * FROM students WHERE Age IN (20,22,24);

#将查询的结果进行排序

mysql>SELECT * FROM students ORDER BY Name {ASC|DESC};

#查询结果别名显示

mysql>SELECT Name AS Stu_Name FROM students;

#LIMIT限定查询结果的条数,LIMIT 2,3表示偏移2条数据后，取3条数据

mysql>SELECT * FROM students LIMIT 2;

#求平均数:AVG()，最大值:MAX() 最小值MIN() 数量:COUNT() 求和:SUM()

mysql>SELECT AVG(age) FROM students;

#分组GROUP BY

mysql>SELECT Age, Gender FROM students GROUP BY Gender;

#别名:AS

mysql>SELECT COUNT(Age) AS Num,Age FROM students GROUP BY Age;

#过滤:HAVING

mysql>SELECT COUNT(Age) AS Num,Age FROM students GROUP BY Age HAVING Num>2;

多表查询:

#指定已哪个字段连接2张表

mysql>SELECT students.Name,courses.Cname FROM students,courses WHERE students.CID1 = courses.CID;

#连接时指定别名

mysql>SELECT students.Name,courses.Cname FROM students,courses WHERE students.CID1 = courses.CID;

#左外连接...LEFT JOIN...ON...

mysql>SELECT s.Name,c.Cname FROM students AS s LEFT JOIN courses AS c ON s.CID1=c.CID;

#右外连接...RIGHT JOIN...ON...

mysql>SELECT s.Name,c.Cname FROM students AS s RIGHT JOIN courses AS c ON s.CID1=c.CID;

子查询

#查询年龄大于平均年龄的数据

mysql>SELECT * FROM students WHERE Age > (SELECT AVG(Age) FROM students);

#在FROM中使用子查询

mysql>SELECT Name,Age FROM (SELECT * FROM students WHERE CID IN (2,3)) AS t WHERE Age>20;

#联合查询

mysql>(SELECT Name,Age FROM students) UNION (SELECT Tname,Age FROM tutors);

创建视图

CREATE VIEW VIEW_NAME AS SELECT....

DCL

----Data Control Language 数据库控制语言如grant,deny,revoke等，只有管理员才有这样的权限。

创建用户

mysql>CREATE USER 'USERNAME'@'HOST' IDENTIFIED BY 'PASSWORD'

删除用户

mysql>DROP USER 'USERNAME'@'HOSHOST支持通配符

_:任意单个字符

%:任意多个字符

授权

mysql>GRANT pri1,pri2...ON DB_NAME.TB_NAME TO 'USERNAME'@'HOST' [IDENTIFIED BY 'PASSWORD']

取消授权

mysql>REVOKE pri1,pri2...ON DB_NAME.TB_NAME FROM 'USERNAME'@'HOST';

查看授权

mysql>SHOW GRANTS FOR 'USERNAME'@'HOST';

EXAMPLE:

mysql>CREATE USER 'lujunyi'@'%' IDENTIFIED BY '';

mysql>SHOW GRANTS FOR 'lujunyi'@'%';

mysql>GRANT ALL PRIVILEGES ON testdb.* TO 'lujunyi'@'%';