msql && sql
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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1
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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)：
|
1
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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
|
1
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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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2
|
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:
|
1
2
|
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
|
1
2
|
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
|
1
|
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
|
1
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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
|
1
|
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
|
1
|
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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1
|
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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1
|
mysql>
SELECT
students.
Name
,courses.Cname
FROM
students,courses
WHERE
students.CID1 = courses.CID;
|
#左外连接...LEFT JION...ON...
|
1
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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...
|
1
|
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
|
1
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mysql>
SELECT
*
FROM
students
WHERE
Age > (
SELECT
AVG
(Age)
FROM
students);
|
#在FROM中使用子查询
|
1
|
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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1
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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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2
3
|
mysql>
CREATE
USER
'lujunyi'
@
'%'
IDENTIFIED
BY
'123456'
;
mysql>SHOW GRANTS
FOR
'lujunyi'
@
'%'
;
mysql>
GRANT
ALL
PRIVILEGES
ON
testdb.*
TO
'lujunyi'
@
'%'
;
|