MySQL,sqlalchemy
Mariadbpython
數據庫是一堆表的集合mysql
主鍵sql
外鍵數據庫
索引編程
安裝：框架
Centos7編程語言
[root@host]# mysqladmin -u root password "new_password"; #建立新密碼
MariaDB [(none)]> show databases; #顯示數據庫 +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | test | +--------------------+ 4 rows in set (0.00 sec)
MariaDB [(none)]> use mysql; #使用mysql數據庫
MariaDB [mysql]> show tables; #顯示mysql數據庫中的全部表 +---------------------------+ | Tables_in_mysql | +---------------------------+ | columns_priv | | db | | event | | func | | general_log | ......
MariaDB [mysql]> desc user; #查看user表結構 +------------------------+-----------------------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +------------------------+-----------------------------------+------+-----+---------+-------+ | Host | char(60) | NO | PRI | | | | User | char(16) | NO | PRI | | | | Password | char(41) | NO | | | | | Select_priv | enum('N','Y') | NO | | N | | | Insert_priv | enum('N','Y') | NO | | N | | | Update_priv | enum('N','Y') | NO | | N | | | Delete_priv | enum('N','Y') | NO | | N | | ......
MariaDB [mysql]> select * from user\G #查看user表中全部的數據
*************************** 1. row *************************** Host: localhost User: root Password: Select_priv: Y Insert_priv: Y Update_priv: Y Delete_priv: Y Create_priv: Y
........
MariaDB [mysql]> select User from user; #從user表中顯示全部的User(用戶) +------+ | User | +------+ | root | | root | | | | whoi | | root | ......
MariaDB [mysql]> GRANT ALL ON test.* TO 'tom'@'localhost' identified by '123'; #在本機建立tom用戶並賦予全部權限在test庫的全部表上，密碼爲123 Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> show grants for 'tom'@'localhost'; # 顯示用戶tom的權限 +------------------------------------------------------------------------------------------------------------+ | Grants for tom@localhost | +------------------------------------------------------------------------------------------------------------+ | GRANT USAGE ON *.* TO 'tom'@'localhost' IDENTIFIED BY PASSWORD '*23AE809DDACAF96AF0FD78ED04B6A265E05AA257' | | GRANT ALL PRIVILEGES ON `test`.* TO 'tom'@'localhost' | +------------------------------------------------------------------------------------------------------------+ 2 rows in set (0.00 sec)
MariaDB [(none)]> create database db; #建立數據庫db Query OK, 1 row affected (0.00 sec)
MariaDB [(none)]> show create database db; # 顯示建立的數據庫db,默認建立的字符集是latin,只能輸入英文 +----------+---------------------------------------------------------------+ | Database | Create Database | +----------+---------------------------------------------------------------+ | db | CREATE DATABASE `db` /*!40100 DEFAULT CHARACTER SET latin1 */ | +----------+---------------------------------------------------------------+ 1 row in set (0.00 sec)
MariaDB [(none)]> create database db_utf charset utf8; #建立字符集爲utf8的數據庫，能夠輸入中文 Query OK, 1 row affected (0.00 sec)
MySQL數據類型ide
經常使用數值spa
SMALLINT3d
INT
FLOAT
日期/時間
字符串
CHAR 定長字符串
VARCHAR 變長字符串
TEXT 長文本數據
MySQL經常使用命令
建立數據表
MariaDB [db]> create table student( # 建立student表
id int auto_increment,
name char(32) not null,
age int not null,
register_date date not null,
primary key (id)); Query OK, 0 rows affected (0.02 sec)
MariaDB [db]> show tables; +--------------+ | Tables_in_db | +--------------+ | student | +--------------+ 1 row in set (0.00 sec)
MariaDB [db]> desc student; +---------------+----------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+----------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(32) | NO | | NULL | | | age | int(11) | NO | | NULL | | | register_date | date | NO | | NULL | | +---------------+----------+------+-----+---------+----------------+ 4 rows in set (0.00 sec)
插入數據
MariaDB [db]> insert into student (name,age,register_date) values ('zhangsan',12,'2017-11-11'); Query OK, 1 row affected (0.01 sec)
MariaDB [db]> select * from student; +----+----------+-----+---------------+ | id | name | age | register_date | +----+----------+-----+---------------+ | 1 | zhangsan | 12 | 2017-11-11 | +----+----------+-----+---------------+ 1 row in set (0.00 sec)
連續插入幾條數據
riaDB [db]> select * from student;
+----+----------+-----+---------------+
| id | name | age | register_date |
+----+----------+-----+---------------+
| 1 | zhangsan | 12 | 2017-11-11 |
| 2 | lisi | 4 | 2017-11-11 |
| 3 | wangwu | 5 | 2017-11-11 |
| 4 | zhaoliu | 8 | 2017-11-11 |
| 5 | hongqi | 28 | 2017-11-11 |
| 6 | hongqi | 28 | 2016-04-11 |
+----+----------+-----+---------------+
6 rows in set (0.00 sec)
查詢數據
MariaDB [db]> select * from student limit 2; #查詢前兩條數據 +----+----------+-----+---------------+ | id | name | age | register_date | +----+----------+-----+---------------+ | 1 | zhangsan | 12 | 2017-11-11 | | 2 | lisi | 4 | 2017-11-11 | +----+----------+-----+---------------+ 2 rows in set (0.00 sec)
MariaDB [db]> select * from student limit 2 offset 1; #偏移一位後查詢兩條 +----+--------+-----+---------------+ | id | name | age | register_date | +----+--------+-----+---------------+ | 2 | lisi | 4 | 2017-11-11 | | 3 | wangwu | 5 | 2017-11-11 | +----+--------+-----+---------------+ 2 rows in set (0.00 sec)
MariaDB [db]> select * from student limit 2 offset 2; #偏移兩位後查詢兩條 +----+---------+-----+---------------+ | id | name | age | register_date | +----+---------+-----+---------------+ | 3 | wangwu | 5 | 2017-11-11 | | 4 | zhaoliu | 8 | 2017-11-11 | +----+---------+-----+---------------+ 2 rows in set (0.00 sec)
where子句
MariaDB [db]> select * from student where id > 3; +----+---------+-----+---------------+ | id | name | age | register_date | +----+---------+-----+---------------+ | 4 | zhaoliu | 8 | 2017-11-11 | | 5 | hongqi | 28 | 2017-11-11 | +----+---------+-----+---------------+ 2 rows in set (0.00 sec)
MariaDB [db]> select * from student where id > 3 and age < 20; +----+---------+-----+---------------+ | id | name | age | register_date | +----+---------+-----+---------------+ | 4 | zhaoliu | 8 | 2017-11-11 | +----+---------+-----+---------------+ 1 row in set (0.00 sec)
MariaDB [db]> select * from student where id=5; +----+--------+-----+---------------+ | id | name | age | register_date | +----+--------+-----+---------------+ | 5 | hongqi | 28 | 2017-11-11 | +----+--------+-----+---------------+ 1 row in set (0.00 sec)
MariaDB [db]> select * from student where register_date like "2016%"; #只取2016年的 +----+--------+-----+---------------+ | id | name | age | register_date | +----+--------+-----+---------------+ | 6 | hongqi | 28 | 2016-04-11 | +----+--------+-----+---------------+ 1 row in set (0.00 sec)
UPDATE語句
MariaDB [db]> update student set name="wangjiu",age=11 where id=3; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0
| 3 | wangjiu | 11 | 2017-11-11 |
DELETE語句
MariaDB [db]> delete from student where name="wangjiu"; Query OK, 1 row affected (0.01 sec)
排序
MariaDB [db]> select * from student order by id desc; #降序排列 +----+----------+-----+---------------+ | id | name | age | register_date | +----+----------+-----+---------------+ | 6 | hongqi | 28 | 2016-04-11 | | 5 | hongqi | 28 | 2017-11-11 | | 4 | zhaoliu | 8 | 2017-11-11 | | 2 | lisi | 4 | 2017-11-11 | | 1 | zhangsan | 12 | 2017-11-11 | +----+----------+-----+---------------+ 5 rows in set (0.00 sec)
作兩條更改
MariaDB [db]> update student set register_date="2017-08-20" where id=2; MariaDB [db]> update student set register_date="2013-01-20" where id=3;
MariaDB [db]> select * from student order by register_date; +----+----------+-----+---------------+ | id | name | age | register_date | +----+----------+-----+---------------+ | 6 | hongqi | 28 | 2016-04-11 | | 2 | lisi | 4 | 2017-08-20 | | 1 | zhangsan | 12 | 2017-11-11 | | 4 | zhaoliu | 8 | 2017-11-11 | | 5 | hongqi | 28 | 2017-11-11 | +----+----------+-----+---------------+ 5 rows in set (0.00 sec)
GROUP BY 分組統計
MariaDB [db]> insert into student (name,age,register_date) values ('zhaoliu',4,'2015-12-20'); Query OK, 1 row affected (0.01 sec)
MariaDB [db]> select * from student; +----+----------+-----+---------------+ | id | name | age | register_date | +----+----------+-----+---------------+ | 1 | zhangsan | 12 | 2017-11-11 | | 2 | lisi | 4 | 2017-08-20 | | 4 | zhaoliu | 8 | 2017-11-11 | | 5 | hongqi | 28 | 2017-11-11 | | 6 | hongqi | 28 | 2016-04-11 | | 7 | zhaoliu | 4 | 2015-12-20 | +----+----------+-----+---------------+ 6 rows in set (0.00 sec)
MariaDB [db]> select name,count(*) from student group by name; +----------+----------+ | name | count(*) | +----------+----------+ | hongqi | 2 | | lisi | 1 | | zhangsan | 1 | | zhaoliu | 2 | +----------+----------+ 4 rows in set (0.00 sec)
MariaDB [db]> select register_date,count(*) from student group by register_date; +---------------+----------+ | register_date | count(*) | +---------------+----------+ | 2015-12-20 | 1 | | 2016-04-11 | 1 | | 2017-08-20 | 1 | | 2017-11-11 | 3 | +---------------+----------+ 4 rows in set (0.01 sec)
MariaDB [db]> select register_date,count(*) as stu_num from student group by register_date; # 用as重命名 +---------------+---------+ | register_date | stu_num | +---------------+---------+ | 2015-12-20 | 1 | | 2016-04-11 | 1 | | 2017-08-20 | 1 | | 2017-11-11 | 3 | +---------------+---------+ 4 rows in set (0.00 sec)
MariaDB [db]> select name,sum(age) from student group by name; # 統計字段之和 +----------+----------+ | name | sum(age) | +----------+----------+ | hongqi | 56 | | lisi | 4 | | zhangsan | 12 | | zhaoliu | 12 | +----------+----------+ 4 rows in set (0.00 sec)
MariaDB [db]> select name,sum(age) from student group by name with rollup; #加起來的總和 +----------+----------+ | name | sum(age) | +----------+----------+ | hongqi | 56 | | lisi | 4 | | zhangsan | 12 | | zhaoliu | 12 | | NULL | 84 | +----------+----------+ 5 rows in set (0.00 sec)
把NULL名改成Total Age
MariaDB [db]> select coalesce(name,'Total Age'),sum(age) from student group by name with rollup; +----------------------------+----------+ | coalesce(name,'Total Age') | sum(age) | +----------------------------+----------+ | hongqi | 56 | | lisi | 4 | | zhangsan | 12 | | zhaoliu | 12 | | Total Age | 84 | +----------------------------+----------+ 5 rows in set (0.00 sec)
修改數據表名或數據表字段
MariaDB [db]> alter table student add sex enum('M','F'); Query OK, 6 rows affected (0.02 sec)
MariaDB [db]> insert into student (name,age,register_date,sex) values('wangsen',22,'2012-04-22','M'); Query OK, 1 row affected (0.00 sec)
MariaDB [db]> select * from student; +----+----------+-----+---------------+------+ | id | name | age | register_date | sex | +----+----------+-----+---------------+------+ | 1 | zhangsan | 12 | 2017-11-11 | NULL | | 2 | lisi | 4 | 2017-08-20 | NULL | | 4 | zhaoliu | 8 | 2017-11-11 | NULL | | 5 | hongqi | 28 | 2017-11-11 | NULL | | 6 | hongqi | 28 | 2016-04-11 | NULL | | 7 | zhaoliu | 4 | 2015-12-20 | NULL | | 8 | wangsen | 22 | 2012-04-22 | M | +----+----------+-----+---------------+------+ 7 rows in set (0.00 sec)
MariaDB [db]> alter table student drop age;
+----+----------+---------------+------+ | id | name | register_date | sex | +----+----------+---------------+------+ | 1 | zhangsan | 2017-11-11 | NULL | | 2 | lisi | 2017-08-20 | NULL | | 4 | zhaoliu | 2017-11-11 | NULL | | 5 | hongqi | 2017-11-11 | NULL | | 6 | hongqi | 2016-04-11 | NULL | | 7 | zhaoliu | 2015-12-20 | NULL | | 8 | wangsen | 2012-04-22 | M | +----+----------+---------------+------+ 7 rows in set (0.00 sec)
MariaDB [db]> desc student;
+---------------+---------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+---------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(32) | NO | | NULL | | | register_date | date | NO | | NULL | | | sex | enum('M','F') | YES | | NULL | | +---------------+---------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec)
MariaDB [db]> alter table student modify sex enum('F','M') not null; #把sex字段改成不能爲空
MariaDB [db]> desc student; +---------------+---------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+---------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(32) | NO | | NULL | | | register_date | date | NO | | NULL | | | sex | enum('F','M') | NO | | NULL | | +---------------+---------------+------+-----+---------+----------------+
更改的另外一種語法:change
MariaDB [db]> alter table student change sex gender char(32) not null default 'X';
MariaDB [db]> select * from student; +----+----------+---------------+--------+ | id | name | register_date | gender | +----+----------+---------------+--------+ | 1 | zhangsan | 2017-11-11 | | | 2 | lisi | 2017-08-20 | | | 4 | zhaoliu | 2017-11-11 | | | 5 | hongqi | 2017-11-11 | | | 6 | hongqi | 2016-04-11 | | | 7 | zhaoliu | 2015-12-20 | | | 8 | wangsen | 2012-04-22 | M | +----+----------+---------------+--------+
MariaDB [db]> desc student; +---------------+----------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+----------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(32) | NO | | NULL | | | register_date | date | NO | | NULL | | | gender | char(32) | NO | | X | | +---------------+----------+------+-----+---------+----------------+
外鍵
特殊的索引，用於關聯兩個表，只能是指定內容
聯合查詢(left join,right join,inner join,full join)
MariaDB [db]> create table A (a int not null); MariaDB [db]> create table B (b int not null); MariaDB [db]> insert into A (a) values(1); MariaDB [db]> insert into A (a) values(2); MariaDB [db]> insert into A (a) values(3); MariaDB [db]> insert into A (a) values(4); MariaDB [db]> insert into B(b) values(3); MariaDB [db]> insert into B(b) values(4); MariaDB [db]> insert into B(b) values(5); MariaDB [db]> insert into B(b) values(6); MariaDB [db]> insert into B(b) values(7);
MariaDB [db]> select * from A; +---+ | a | +---+ | 1 | | 2 | | 3 | | 4 | +---+ 4 rows in set (0.01 sec) MariaDB [db]> select * from B; +---+ | b | +---+ | 3 | | 4 | | 5 | | 6 | | 7 | +---+ 5 rows in set (0.00 sec)
交集（inner join）
MariaDB [db]> select * from A inner join B on A.a = B.b; # 經常使用 +---+---+ | a | b | +---+---+ | 3 | 3 | | 4 | 4 | +---+---+
或
MariaDB [db]> select A.*,B.* from A,B where A.a =B.b; +---+---+ | a | b | +---+---+ | 3 | 3 | | 4 | 4 | +---+---+
差集（Left join,right join）
MariaDB [db]> select * from A left join B on A.a = B.b; +---+------+ | a | b | +---+------+ | 3 | 3 | | 4 | 4 | | 1 | NULL | | 2 | NULL |
MariaDB [db]> select * from A right join B on A.a = B.b; +------+---+ | a | b | +------+---+ | 3 | 3 | | 4 | 4 | | NULL | 5 | | NULL | 6 | | NULL | 7 | +------+---+
並集（full join）,可是mysql不支持
MariaDB [db]> select * from A left join B on A.a = B.b union select * from A right join B on A.a=B.b; +------+------+ | a | b | +------+------+ | 3 | 3 | | 4 | 4 | | 1 | NULL | | 2 | NULL | | NULL | 5 | | NULL | 6 | | NULL | 7 | +------+------+ 7 rows in set (0.00 sec)
事物
原子性
穩定性
隔離性
可靠性
索引
MariaDB [db]> select * from student; +----+----------+---------------+--------+ | id | name | register_date | gender | +----+----------+---------------+--------+ | 1 | zhangsan | 2017-11-11 | | | 2 | lisi | 2017-08-20 | | | 4 | zhaoliu | 2017-11-11 | | | 5 | hongqi | 2017-11-11 | | | 6 | hongqi | 2016-04-11 | | | 7 | zhaoliu | 2015-12-20 | | | 8 | wangsen | 2012-04-22 | M | +----+----------+---------------+--------+
MariaDB [db]> create index index_name on student(name); # 建立索引
MariaDB [db]> show index from student; +---------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | +---------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | student | 0 | PRIMARY | 1 | id | A | 7 | NULL | NULL | | BTREE | | | | student | 1 | index_name | 1 | name | A | 7 | NULL | NULL | | BTREE | | | +---------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
MariaDB [db]> drop index index_name on student; # 刪除索引
惟一索引
索引列的值必須惟一，但容許有空值。若是是組合索引，則列值得組合必須惟一
python操做mysql
python-mysqldb
yum install MySQL-python # 3.0不能用
pymysql
pip3 install pymysql # 適用於3.0版本
SQLAlchemy
SQLALchemy是python下的一款ORM框架，該框架創建在數據庫API之上，使用關係對象映射進行數據庫操做。將對象轉換成SQL，而後使用數據API執行SQL並獲取執行結果
pip3 install SQLAlchemy
ORM介紹
對象關係映射，經過orm將編程語言模型和數據庫的關係模型創建映射關係，這樣在使用編程語言對數據庫進行操做的時候能夠直接使用編程語言的對象模型進行操做就能夠了，而不用直接使用sql語言
優勢：
1.隱藏數據訪問細節，封閉通用數據庫交互，徹底不用考慮SQL語句
2.構造數據庫結構更簡單方便
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