数值型:
TINYINT 1 ,SMALLINT 2,MEDIUMINT 3 ,INT 4,BIGINT 8,DECIMAL,FLOAT 4,DOUBLE 8,BIT
字符串型
CHAR,VARCHAR,BINARY,VBINARY,TINYBLOB,BLOB,MEDIUMBLOB,LONGBLOG,TINYTEXT,TEXT,MEDIUMTEXT,LONGTEXT,EMUM,SET
日期时间型
date,time,datetime,timestamp
数据限定修饰:
NOT NULL,NULL,DEFAULT,AUTO_INCREMENT,UNSIGNED,PRIMARY KEY,UNIQUE KEY,FOREIGN KEY
CHARACTER SET #ps:SHOW CHARACTER SET 显示当前数据库所支持的所有字符集
COLLATION #ps:SHOW COLLATION 显示所支持的所有排序规则
以下是SQL的每种DDL,DCL,DML语言
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
创建一张新表
CRTATE TABLE [IF NOT EXISTS] TBNAME(col_name col_definition,...) |
EXAMPLE:
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mysql> CREATE
TABLE students(Id
INT PRIMARY
KEY NOT NULL
AUTO_INCREMENT UNSIGNED, Name
CHAR (20) UNIQUE
KEY NOT
NULL ,Age TINYINT UNSIGNED INDEX ,Gender
CHAR (1) NOT
NULL ) [ENGINE={MyISAM | InnoDB }]; |
也可以这样写(区别在于单独定义主键,唯一键和索引):
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mysql> CREATE
TABLE students(Id
INT NOT
NULL AUTO_INCREMENT UNSIGNED, Name
CHAR (20) NOT
NULL ,Age TINYINT UNSIGNED,Gender
CHAR (1) NOT
NULL , PRIMARY
KEY (id), UNIQUE
KEY ( name ), INDEX (age)) |
查询出一张表的数据后创建新表(字段定义会丢失,数据会保留)
CREATE TABLE TBNAME SELECT... |
EXAMPLE:
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mysql> CREATE
TABLE test SELECT
* FROM
students WHERE Id>5; |
以一张表的格式定义,创建一张新的空表
CREATE TABLE TBNAME1 LIKE TBNAME2 |
修改表:
ALTER TABLE tb_name MODIFY #修改字段定义 CHANGE #可以修改字段名和字段定义 ADD DROP |
EXAMPLE:
给表添加字段
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mysql> ALTER
TABLE students ADD
(course VARCHAR (100),teacher
CHAR (20)); |
添加惟一键
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mysql> ALTER
TABLE students ADD
UNIQUE KEY
Name ; |
修改字段:
修改course字段为Course字段,并放在Name字段之后(修改字段需要带上新的字段的定义)ps:MODIFY只能修改字段定义
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mysql> ALTER
TABLE students CHANGE course Course
VARCHAR (100) [ AFTER
Name ]; |
重命名表名
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mysql> ALTER
TABLE students RENAME
TO stu; mysql>RENAME
TABLE stu TO
students; |
添加一个外键约束
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ALTER
TABLE students ADD
FOREIGN KEY
foreign _cid (CID) REFERENCES
course (CID); |
创建索引
CREATE INDEX index_name ON TABLE (col_name[(length)] [ASC|DESC]) [USING {BTREE|HASH}]; |
删除索引
DROP INDEX index_name ON TBNAME; |
查看表状态:SHOW STATUS LIKE 'TBNAME';
查看表的索引:SHOW INDEXES FROM TBNAME;
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
#如果每个字段都有值,不需要写字段名称,每组值用,隔开
mysql>INSERT INTO tb_name (col1,col2) VALUES ('STRING',NUM),('STRING',NUM); mysql>INSERT INTO tb_name SET col1='string',col2='string'; mysql>INSERT INTO tb_name (col1,col2,col3) SELECT...; |
EXAMPLE:
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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
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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; |
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mysql> DELETE
FROM students WHERE
Course= 'mysql' ; |
清空表:将会重置计数器
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
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mysql> SELECT
Name ,teacher FROM
students WHERE
Name = 'wusong' ; |
#重复的结果只显示一次
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mysql> SELECT
DISTINCT Gender FROM
students; |
#组合条件,可以使用AND,OR,NOT,XOR组合多个条件
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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
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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
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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
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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)
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mysql> SELECT
* FROM
students WHERE Age
IN (20,22,24); |
#将查询的结果进行排序
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mysql> SELECT
* FROM
students ORDER
BY Name { ASC | DESC }; |
#查询结果别名显示
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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
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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()
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mysql> SELECT
AVG (age) FROM
students; |
#分组GROUP BY
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mysql> SELECT
Age, Gender FROM
students GROUP
BY Gender; |
#别名:AS
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mysql> SELECT
COUNT (Age) AS
Num,Age FROM
students GROUP
BY Age; |
#过滤:HAVING
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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
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mysql> SELECT
students. Name ,courses.Cname
FROM students,courses
WHERE students.CID1 = courses.CID; |
#连接时指定别名
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mysql> SELECT
students. Name ,courses.Cname
FROM students,courses
WHERE students.CID1 = courses.CID; |
#左外连接...LEFT JION...ON...
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mysql> SELECT
s. Name ,c.Cname
FROM students
AS s LEFT
JION courses AS
c ON s.CID1=c.CID; |
#右外连接...RIGHT JION...ON...
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mysql> SELECT
s. Name ,c.Cname
FROM students
AS s RIGHT
JION courses AS
c ON s.CID1=c.CID; |
子查询
#查询年龄大于平均年龄的数据
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mysql> SELECT
* FROM
students WHERE Age > ( SELECT
AVG (Age) FROM
students); |
#在FROM中使用子查询
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mysql> SELECT
Name ,Age FROM
( SELECT
* FROM students
WHERE CID IN
(2,3)) AS
t WHERE Age>20; |
#联合查询
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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:
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mysql> CREATE
USER 'lujunyi' @ '%'
IDENTIFIED BY
'123456' ; mysql>SHOW GRANTS
FOR 'lujunyi' @ '%' ; mysql> GRANT
ALL PRIVILEGES
ON testdb.* TO
'lujunyi' @ '%' ; |