python15-day12rabbitmq和mysql

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1. 消息的批量分发 

之前的例子都是一对一发送与接收,有时需要让消息被所有的queue收到,类似广播效果,这时候需要exchange了。

exchange在定义的时候是有类型的,以决定那些queue符合条件,可以接受消息。

l  fanout:所有的bind到此exchangequeue都可以接收消息,纯广播了。

l  direct:通过routingkeyexchange决定的哪一个唯一的queue可以接受消息。

l  topic:所有符合routingKey(可以是一个表达式)的所bindqueue可以接收消息。

l  headers:通过headers来决定把消息发送给哪些queue。(不常用)

1.1 fanout方式(广播)

发送端:

import pika
import sys

username =
‘python‘   #指定远程rabbitmq的用户名密码
pwd = ‘python‘
user_pwd = pika.PlainCredentials(username, pwd)
connection = pika.BlockingConnection(pika.ConnectionParameters(
‘192.168.56.15‘, credentials=user_pwd))
# connection = pika.BlockingConnection(pika.ConnectionParameters(host=‘192.168.56.15‘))
channel = connection.channel()
channel.exchange_declare(
exchange="logs",type=‘fanout‘)
message =
‘ ‘.join(sys.argv[1:]) or "info:Hello World!"
channel.basic_publish(exchange = ‘logs‘,routing_key=‘‘,body=message)
print("[x] sent %r" %message)
connection.close()

接收端(可以定义多个接收端):

import pika
import sys
username =
‘python‘   #指定远程rabbitmq的用户名密码
pwd = ‘python‘
user_pwd = pika.PlainCredentials(username, pwd)
connection = pika.BlockingConnection(pika.ConnectionParameters(
‘192.168.56.15‘, credentials=user_pwd))

channel=connection.channel()

channel.exchange_declare(
exchange="logs",type=‘fanout‘)

result = channel.queue_declare(
exclusive=True)
queue_name = result.method.queue
channel.queue_bind(
exchange="logs",queue=queue_name)
print("[x] Waitting for logs.To exit press CTRL+C")

def callback(ch,method,properties,body):
   
print("[x] %r "%body)
channel.basic_consume(callback,
queue=queue_name,no_ack=True)

channel.start_consuming()

这样可以实现一对多的发送,即一个生产者多个消费者。

1.2 direct方式(关键字)

sent端:

import pika
import sys
username =
‘python‘   #指定远程rabbitmq的用户名密码
pwd = ‘python‘
user_pwd = pika.PlainCredentials(username, pwd)
connection = pika.BlockingConnection(pika.ConnectionParameters(
‘192.168.56.15‘, credentials=user_pwd))

channel = connection.channel()

channel.exchange_declare(
exchange="direct_log",type="direct")

severity = sys.argv[
1] if len(sys.argv) > 1 else "info"
message = " ".join(sys.argv[2:]) or "hello world"
channel.basic_publish(exchange="direct_log",routing_key=severity,body=message)

print("[x] sent %r:%r" %(severity,message))
connection.close()

receive端:

import pika
import sys
username =
‘python‘   #指定远程rabbitmq的用户名密码
pwd = ‘python‘
user_pwd = pika.PlainCredentials(username, pwd)
connection = pika.BlockingConnection(pika.ConnectionParameters(
‘192.168.56.15‘, credentials=user_pwd))
channel = connection.channel()

channel.exchange_declare(
exchange="direct_log",type="direct")
result = channel.queue_declare(
exclusive=True)

queue_name = result.method.queue

severities = sys.argv[
1:]

if not severities:
    sys.stderr.write(
"usage: %s [info] [warning] [error]\\n"%sys.argv[0])
    sys.exit(
1)
for severity in severities:
    channel.queue_bind(
exchange="direct_log",queue=queue_name,routing_key=severity)

print("[*] waiting for logs to exit press ctrl+c")

def callback(ch,method,properties,body):
   
print("[x] %r:%r" %(method.routing_key,body))
channel.basic_consume(callback,
queue=queue_name,no_ack=True)

channel.start_consuming()

执行结果:

技术分享

1.3 topic方式(消息过滤)

技术分享

To receive all the logs run:

python receive_logs_topic.py "#"

To receive all logs from the facility "kern":

python receive_logs_topic.py "kern.*"

Or if you want to hear only about "critical" logs:

python receive_logs_topic.py "*.critical"

You can create multiple bindings:

python receive_logs_topic.py "kern.*" "*.critical"

And to emit a log with a routing key "kern.critical" type:

python emit_log_topic.py "kern.critical" "A critical kernel error"

 

 

发送端:

import pika
import sys
username =
‘python‘   #指定远程rabbitmq的用户名密码
pwd = ‘python‘
user_pwd = pika.PlainCredentials(username, pwd)
connection = pika.BlockingConnection(pika.ConnectionParameters(
‘192.168.56.15‘, credentials=user_pwd))

channel = connection.channel()

channel.exchange_declare(
exchange="topci_log",type="topic")

severity = sys.argv[
1] if len(sys.argv) > 1 else "info"
message = " ".join(sys.argv[2:]) or "hello world"
channel.basic_publish(exchange="topic_log",routing_key=severity,body=message)

print("[x] sent %r:%r" %(severity,message))
connection.close()

 

消费者:

import pika
import sys
username =
‘python‘   #指定远程rabbitmq的用户名密码
pwd = ‘python‘
user_pwd = pika.PlainCredentials(username, pwd)
connection = pika.BlockingConnection(pika.ConnectionParameters(
‘192.168.56.15‘, credentials=user_pwd))
channel = connection.channel()

channel.exchange_declare(
exchange="topic_log",type="topic")
result = channel.queue_declare(
exclusive=True)

queue_name = result.method.queue

severities = sys.argv[
1:]

if not severities:
    sys.stderr.write(
"usage: %s [binding key....]\\n"%sys.argv[0])
    sys.exit(
1)
for severity in severities:
    channel.queue_bind(
exchange="topic_log",queue=queue_name,routing_key=severity)

print("[*] waiting for logs to exit press ctrl+c")

def callback(ch,method,properties,body):
   
print("[x] %r:%r" %(method.routing_key,body))
channel.basic_consume(callback,
queue=queue_name,no_ack=True)

channel.start_consuming()

备注:和direct基本是一样的,把direct改为topic即可。

 

结果:

技术分享

 

2. 数据库

什么是数据库?

数据库(Database)是按照数据结构来组织、存储和管理数据的仓库,
每个数据库都有一个或多个不同的API用于创建,访问,管理,搜索和复制所保存的数据。
我们也可以将数据存储在文件中,但是在文件中读写数据速度相对较慢。
所以,现在我们使用关系型数据库管理系统(RDBMS)来存储和管理的大数据量。所谓的关系型数据库,是建立在关系模型基础上的数据库,借助于集合代数等数学概念和方法来处理数据库中的数据。
       RDBMS即关系数据库管理系统(Relational Database Management System)的特点:
       1.数据以表格的形式出现
       2.
每行为各种记录名称
       3.
每列为记录名称所对应的数据域
       4.
许多的行和列组成一张表单
       5.
若干的表单组成database

2.1 建表语句

mysql> create table students(stu_id int AUTO_INCREMENT,name char(32),age int,register_date DATE,primary key (stu_id));

Query OK, 0 rows affected (0.03 sec)

 

mysql> show tables;

+-------------------+

| Tables_in_student |

+-------------------+

| students          |

+-------------------+

1 row in set (0.00 sec)

2.2 插入语句

mysql> insert into students (name,age,register_date) values ("liangkai",30,"20161228");

Query OK, 1 row affected (0.01 sec)

 

mysql> select * from students;

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liangkai |   30 | 2016-12-28    |

+--------+----------+------+---------------+

1 row in set (0.00 sec)

2.3 查询语句

mysql> select name,age from students where age >=30;   #条件查询

+----------+------+

| name     | age  |

+----------+------+

| liangkai |   30 |

| xuliqing |   31 |

+----------+------+

2 rows in set (0.00 sec)

 

mysql> select stu_id,name,age from students limit 2 offset 2; #指定范围

+--------+----------+------+

| stu_id | name     | age  |

+--------+----------+------+

|      3 | xiaoqing |   25 |

|      4 | kaige    |   24 |

+--------+----------+------+

2 rows in set (0.00 sec)

 

mysql> select stu_id,name,age from students limit 2 offset 1;

+--------+----------+------+

| stu_id | name     | age  |

+--------+----------+------+

|      2 | xuliqing |   31 |

|      3 | xiaoqing |   25 |

+--------+----------+------+

2 rows in set (0.00 sec)

 

mysql> select name,age from students where age >30 or age <25;

+----------+------+

| name     | age  |

+----------+------+

| xuliqing |   31 |

| kaige    |   24 |

+----------+------+

2 rows in set (0.00 sec)

 

备注:使用主键来作为 WHERE 子句的条件查询是非常快速的。

where like语句:

mysql> select * from students where name like "%ng%";

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

+--------+----------+------+---------------+

2 rows in set (0.01 sec)

 

mysql> select * from students where name like "liang%";

+--------+-------+------+---------------+

| stu_id | name  | age  | register_date |

+--------+-------+------+---------------+

|      1 | liang |   23 | 2016-12-28    |

+--------+-------+------+---------------+

1 row in set (0.00 sec)

 

mysql>

2.4 修改语句

mysql> select * from students;                                 

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | xuliqing |   31 | 2016-12-28    |

|      3 | xiaoqing |   25 | 2015-12-25    |

|      4 | kaige    |   24 | 2015-07-10    |

+--------+----------+------+---------------+

4 rows in set (0.00 sec)

 

mysql> update students set name="qingqing",age=22 where stu_id = 2;

Query OK, 1 row affected (0.01 sec)

Rows matched: 1  Changed: 1  Warnings: 0

 

mysql> update students set name="disanzhe",age=100 where stu_id > 2;           

Query OK, 2 rows affected (0.00 sec)

Rows matched: 2  Changed: 2  Warnings: 0

 

mysql> select * from students;                                     

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

|      3 | disanzhe |  100 | 2015-12-25    |

|      4 | disanzhe |  100 | 2015-07-10    |

+--------+----------+------+---------------+

4 rows in set (0.00 sec)

 

2.5 删除语句

mysql> select * from students;                                     

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

|      3 | disanzhe |  100 | 2015-12-25    |

|      4 | disanzhe |  100 | 2015-07-10    |

+--------+----------+------+---------------+

4 rows in set (0.00 sec)

 

mysql> delete from students where stu_id >2;

Query OK, 2 rows affected (0.01 sec)

 

mysql> select * from students;             

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

+--------+----------+------+---------------+

2 rows in set (0.00 sec)

2.6 排序

mysql> select * from students order by age;

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      2 | qingqing |   22 | 2016-12-28    |

|      1 | liang    |   23 | 2016-12-28    |

|      5 | xiaoming |   32 | 2015-11-24    |

|      6 | xiaohong |   43 | 2012-11-24    |

|      8 | jack     |   46 | 2008-11-24    |

|      7 | JACK     |   56 | 2002-11-24    |

+--------+----------+------+---------------+

6 rows in set (0.00 sec)

 

mysql> select * from students order by age desc;

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      7 | JACK     |   56 | 2002-11-24    |

|      8 | jack     |   46 | 2008-11-24    |

|      6 | xiaohong |   43 | 2012-11-24    |

|      5 | xiaoming |   32 | 2015-11-24    |

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

+--------+----------+------+---------------+

6 rows in set (0.00 sec)

备注:使用 ASC  DESC 关键字来设置查询结果是按升序或降序排列。 默认情况下,它是按升序排列。

2.7 mysql group by语句

mysql> select * from students;

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

|      5 | xiaoming |   32 | 2016-12-28    |

|      6 | xiaohong |   43 | 2016-12-28    |

|      7 | JACK     |   56 | 2016-12-28    |

|      8 | jack     |   46 | 2016-12-28    |

+--------+----------+------+---------------+

6 rows in set (0.00 sec)

mysql> select register_date,count(register_date) from students group by register_date;       #每天注册有多少人

+---------------+----------------------+

| register_date | count(register_date) |

+---------------+----------------------+

| 2016-12-28    |                    6 |

+---------------+----------------------+

1 row in set (0.00 sec)

 

mysql> select avg(age) from students;   #统计平均年龄

+----------+

| avg(age) |

+----------+

|  37.0000 |

+----------+

1 row in set (0.00 sec)

 

mysql> select sum(age) from students;    #统计所有人年龄之和

+----------+

| sum(age) |

+----------+

|      222 |

+----------+

1 row in set (0.00 sec)

mysql>

 

mysql> select coalesce(register_date,"total"),count(register_date) from students group by register_date with rollup;

+---------------------------------+----------------------+

| coalesce(register_date,"total") | count(register_date) |

+---------------------------------+----------------------+

| 2016-12-28                      |                    6 |

| total                           |                    6 |

+---------------------------------+----------------------+

2 rows in set (0.00 sec)

 

mysql>

2.8 添加字段

mysql> alter table students add core int not null;   #添加字段

Query OK, 6 rows affected (0.02 sec)

Records: 6  Duplicates: 0  Warnings: 0

mysql> select * from students;                   

+--------+----------+------+---------------+------+

| stu_id | name     | age  | register_date | core |

+--------+----------+------+---------------+------+

|      1 | liang    |   23 | 2016-12-28    |    0 |

|      2 | qingqing |   22 | 2016-12-28    |    0 |

|      5 | xiaoming |   32 | 2016-12-28    |    0 |

|      6 | xiaohong |   43 | 2016-12-28    |    0 |

|      7 | JACK     |   56 | 2016-12-28    |    0 |

|      8 | jack     |   46 | 2016-12-28    |    0 |

+--------+----------+------+---------------+------+

6 rows in set (0.00 sec)

mysql> alter table students drop core;  #删除一个字段

Query OK, 6 rows affected (0.02 sec)

Records: 6  Duplicates: 0  Warnings: 0

 

mysql> select * from students;       

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

|      5 | xiaoming |   32 | 2016-12-28    |

|      6 | xiaohong |   43 | 2016-12-28    |

|      7 | JACK     |   56 | 2016-12-28    |

|      8 | jack     |   46 | 2016-12-28    |

+--------+----------+------+---------------+

6 rows in set (0.00 sec)

修改字段:

alter table students modify name char(8);

alter table students change name1 name2 date

mysql> select * from students;     

+--------+----------+------+---------------+

| stu_id | name     | age  | register_date |

+--------+----------+------+---------------+

|      1 | liang    |   23 | 2016-12-28    |

|      2 | qingqing |   22 | 2016-12-28    |

|      5 | xiaoming |   32 | 2016-12-28    |

|      6 | xiaohong |   43 | 2016-12-28    |

|      7 | JACK     |   56 | 2016-12-28    |

|      8 | jack     |   46 | 2016-12-28    |

+--------+----------+------+---------------+

6 rows in set (0.00 sec)

 

mysql> alter table students modify name char(8);  #修改字段类型 

Query OK, 6 rows affected (0.03 sec)

Records: 6  Duplicates: 0  Warnings: 0

 

mysql> alter table students change register_date regi_date date;#修改字段名

Query OK, 6 rows affected (0.02 sec)

Records: 6  Duplicates: 0  Warnings: 0

 

mysql> select * from students;                      +--------+----------+------+------------+

| stu_id | name     | age  | regi_date  |

+--------+----------+------+------------+

|      1 | liang    |   23 | 2016-12-28 |

|      2 | qingqing |   22 | 2016-12-28 |

|      5 | xiaoming |   32 | 2016-12-28 |

|      6 | xiaohong |   43 | 2016-12-28 |

|      7 | JACK     |   56 | 2016-12-28 |

|      8 | jack     |   46 | 2016-12-28 |

+--------+----------+------+------------+

6 rows in set (0.00 sec)

 

mysql> desc students;

+-----------+---------+------+-----+---------+----------------+

| Field     | Type    | Null | Key | Default | Extra          |

+-----------+---------+------+-----+---------+----------------+

| stu_id    | int(11) | NO   | PRI | NULL    | auto_increment |

| name      | char(8) | YES  |     | NULL    |                |

| age       | int(11) | YES  |     | NULL    |                |

| regi_date | date    | YES  |     | NULL    |                |

+-----------+---------+------+-----+---------+----------------+

4 rows in set (0.00 sec)

mysql> alter table students modify stu_id int(8);

Query OK, 6 rows affected (0.03 sec)

Records: 6  Duplicates: 0  Warnings: 0

 

mysql> desc students;                            

+-----------+---------+------+-----+---------+-------+

| Field     | Type    | Null | Key | Default | Extra |

+-----------+---------+------+-----+---------+-------+

| stu_id    | int(8)  | NO   | PRI | 0       |       |

| name      | char(8) | YES  |     | NULL    |       |

| age       | int(11) | YES  |     | NULL    |       |

| regi_date | date    | YES  |     | NULL    |       |

+-----------+---------+------+-----+---------+-------+

4 rows in set (0.00 sec)

2.9 事务

MySQL 事务主要用于处理操作量大,复杂度高的数据。比如说,在人员管理系统中,你删除一个人员,你即需要删除人员的基本资料,也要删除和该人员相关的信息,如信箱,文章等等,这样,这些数据库操作语句就构成一个事务!

l  MySQL中只有使用了Innodb数据库引擎的数据库或表才支持事务

l  事务处理可以用来维护数据库的完整性,保证成批的SQL语句要么全部执行,要么全部不执行

l  事务用来管理insert,update,delete语句

一般来说,事务是必须满足4个条件(ACID): Atomicity(原子性)、Consistency(稳定性)、Isolation(隔离性)、Durability(可靠性)

l  事务的原子性:一组事务,要么成功;要么撤回。

l  稳定性  有非法数据(外键约束之类),事务撤回。

l  隔离性:事务独立运行。一个事务处理后的结果,影响了其他事务,那么其他事务会撤回。事务的100%隔离,需要牺牲速度。

l  可靠性:软、硬件崩溃后,InnoDB数据表驱动会利用日志文件重构修改。可靠性和高速度不可兼得, innodb_flush_log_at_trx_commit选项 决定什么时候吧事务保存到日志里。

例如:

mysql> select * from students;

+--------+----------+------+------------+

| stu_id | name     | age  | regi_date  |

+--------+----------+------+------------+

|      1 | liang    |   23 | 2016-12-28 |

|      2 | qingqing |   22 | 2016-12-28 |

|      5 | xiaoming |   32 | 2016-12-28 |

|      6 | xiaohong |   43 | 2016-12-28 |

|      7 | JACK     |   56 | 2016-12-28 |

|      8 | jack     |   46 | 2016-12-28 |

+--------+----------+------+------------+

6 rows in set (0.00 sec)

 

mysql> begin;     #开启一个事务

Query OK, 0 rows affected (0.00 sec)

mysql> delete from students where stu_id=7;   #删除一条数据   

Query OK, 1 row affected (0.00 sec)

 

mysql> update students set name="xiaoqing",age=25 where stu_id=2;   #修改

Query OK, 1 row affected (0.00 sec)

Rows matched: 1  Changed: 1  Warnings: 0

 

mysql> select * from students;

+--------+----------+------+------------+

| stu_id | name     | age  | regi_date  |

+--------+----------+------+------------+

|      1 | liang    |   23 | 2016-12-28 |

|      2 | xiaoqing |   25 | 2016-12-28 |

|      5 | xiaoming |   32 | 2016-12-28 |

|      6 | xiaohong |   43 | 2016-12-28 |

|      8 | jack     |   46 | 2016-12-28 |

+--------+----------+------+------------+

5 rows in set (0.00 sec)

 

mysql> rollback;     #返回事务,这样数据是不会写入的,返回到begin的时候,如果想写到库里,执行commit

Query OK, 0 rows affected (0.01 sec)

 

mysql> select * from students;

+--------+----------+------+------------+

| stu_id | name     | age  | regi_date  |

+--------+----------+------+------------+

|      1 | liang    |   23 | 2016-12-28 |

|      2 | qingqing |   22 | 2016-12-28 |

|      5 | xiaoming |   32 | 2016-12-28 |

|      6 | xiaohong |   43 | 2016-12-28 |

|      7 | JACK     |   56 | 2016-12-28 |

|      8 | jack     |   46 | 2016-12-28 |

+--------+----------+------+------------+

6 rows in set (0.00 sec)

 

mysql>

2.10 索引

mySQL索引的建立对于MySQL的高效运行是很重要的,索引可以大大提高MySQL的检索速度。

       打个比方,如果合理的设计且使用索引的MySQL是一辆兰博基尼的话,那么没有设计和使用索引的MySQL就是一个人力三轮车。

       索引分单列索引和组合索引。单列索引,即一个索引只包含单个列,一个表可以有多个单列索引,但这不是组合索引。组合索引,即一个索包含多个列。

       创建索引时,你需要确保该索引是应用在 SQL 查询语句的条件(一般作为 WHERE 子句的条件) 实际上,索引也是一张表,该表保存了主键与索引字段,并指向实体表的记录。

       上面都在说使用索引的好处,但过多的使用索引将会造成滥用。因此索引也会有它的缺点:虽然索引大大提高了查询速度,同时却会降低更新表的速度,如对表进行INSERTUPDATEDELETE。因为更新表时,MySQL不仅要保存数据,还要保存一下索引文件。建立索引会占用磁盘空间的索引文件。

普通索引

创建索引

这是最基本的索引,它没有任何限制。它有以下几种创建方式:

CREATE INDEX indexName ON mytable(username(length));  

如果是CHARVARCHAR类型,length可以小于字段实际长度;如果是BLOBTEXT类型,必须指定 length

 修改表结构

ALTER mytable ADD INDEX [indexName] ON (username(length))

创建表的时候直接指定

CREATE TABLE mytable(  

ID INT NOT NULL,  

username VARCHAR(16) NOT NULL,  

INDEX [indexName] (username(length)) 

); 

删除索引的语法

DROP INDEX [indexName] ON mytable;

唯一索引

它与前面的普通索引类似,不同的就是:索引列的值必须唯一,但允许有空值。如果是组合索引,则列值的组合必须唯一。它有以下几种创建方式:

创建索引

创建索引

CREATE UNIQUE INDEX indexName ON mytable(username(length))

修改表结构

ALTER mytable ADD UNIQUE [indexName] ON (username(length))

创建表的时候直接指定

CREATE TABLE mytable(  

ID INT NOT NULL,    

username VARCHAR(16) NOT NULL,  

UNIQUE [indexName] (username(length)) 

); 

使用ALTER 命令添加和删除索引

有四种方式来添加数据表的索引:

ALTER TABLE tbl_name ADD PRIMARY KEY (column_list): 该语句添加一个主键,这意味着索引值必须是唯一的,且不能为NULL

ALTER TABLE tbl_name ADD UNIQUE index_name (column_list): 这条语句创建索引的值必须是唯一的(除了NULL外,NULL可能会出现多次)。

ALTER TABLE tbl_name ADD INDEX index_name (column_list): 添加普通索引,索引值可出现多次。

ALTER TABLE tbl_name ADD FULLTEXT index_name (column_list):该语句指定了索引为 FULLTEXT ,用于全文索引。

以下实例为在表中添加索引。

mysql> ALTER TABLE testalter_tbl ADD INDEX (c);

你还可以在 ALTER 命令中使用 DROP 子句来删除索引。尝试以下实例删除索引:

mysql> ALTER TABLE testalter_tbl DROP INDEX (c);

使用 ALTER 命令添加和删除主键

主键只能作用于一个列上,添加主键索引时,你需要确保该主键默认不为空(NOT NULL)。实例如下:

mysql> ALTER TABLE testalter_tbl MODIFY i INT NOT NULL;

mysql> ALTER TABLE testalter_tbl ADD PRIMARY KEY (i);

你也可以使用 ALTER 命令删除主键:

mysql> ALTER TABLE testalter_tbl DROP PRIMARY KEY;

删除指定时只需指定PRIMARY KEY,但在删除索引时,你必须知道索引名。

显示索引信息

mysql> SHOW INDEX FROM table_name\\G

2.11 外键关联

create_table_class = cursor.execute("create table class(cid INT AUTO_INCREMENT,caption CHAR(32),PRIMARY KEY (cid))")
create_table_student = cursor.execute("create table student(sid int auto_increment,"
                                      "sname char(32),"
                                      "gender char(16),"
                                      "class_id int(8),"
                                      "primary key (sid),"
                                      "KEY fk_class_id (class_id),"
                                      "CONSTRAINT fk_class_id FOREIGN KEY (class_id) REFERENCES class (cid))")


create_table_teacher = cursor.execute("create table teacher(tid INT AUTO_INCREMENT,tname CHAR(32),PRIMARY KEY (tid))")
create_table_course = cursor.execute("create table course(cid INT AUTO_INCREMENT,"
                                     "cname CHAR(32),"
                                     "teacher_id INT(8),"
                                     "PRIMARY KEY (cid),"
                                     "KEY fk_course_id (teacher_id),"
                                     "CONSTRAINT fk_course_id FOREIGN KEY (teacher_id) REFERENCES teacher (tid))")
   # fk_course_id
外键名,可随意设定
create_table_score = cursor.execute("create table score(sid INT AUTO_INCREMENT,"
                                    "student_id int(8),"
                                    "course_id INT(8),"
                                    "number int(8),"
                                    "PRIMARY KEY (sid),"
                                    "KEY fk_score1_id (student_id),"
                                    "CONSTRAINT fk_score1_id FOREIGN KEY (student_id) REFERENCES student (sid),"
                                    "KEY fk_score2_id (course_id),"
                                    "CONSTRAINT fk_score1_id FOREIGN KEY (course_id) REFERENCES course (cid))")

多表联表查询:

mysql> select student.sname,course.cname,score.number from score inner join course on course.cid = score.course_id  inner join student on student.sid = score.student_id;

+--------+--------+--------+

| sname  | cname  | number |

+--------+--------+--------+

| 铁锤   | 生物   |     60 |

| 铁锤   | 体育   |     43 |

| 钢弹   | 体育   |    100 |

| 铁锤   | 物理   |     65 |

| 钢弹   | 物理   |     55 |

| 钢弹   | 生物   |     99 |

| 山炮   | 生物   |     73 |

| 山炮   | 体育   |     59 |

| 山炮   | 物理   |     30 |

+--------+--------+--------+

9 rows in set (0.00 sec)

 

mysql练习题 http://www.cnblogs.com/wupeiqi/articles/5729934.html  

更多mysql知识,请看http://www.cnblogs.com/wupeiqi/articles/5713323.html

3. pymysql

3.1 连接数据库

在数据库创建python库,以及python的用户名密码,允许所有用户访问该数据库。并创建表host,插入数据。

create table host(host_id int(8) AUTO_INCREMENT,host char(32),primary key (host_id));

insert into host (host) values ("1.1.1.1");

查询创建结果:

mysql> select * from python.host;                   

+---------+---------+

| host_id | host    |

+---------+---------+

|       1 | 1.1.1.1 |

+---------+---------+

1 row in set (0.00 sec)

pycharm创建脚本连接数据库:

import pymysql
conn = pymysql.connect(
host="192.168.56.15",port=3306,user="python",password="123456",charset=‘utf8‘) #如果插入的数据中有中文,需要指定字符编码集
cursor =conn.cursor()

cursor.execute(‘create database if not exists python‘)

cursor.execute(‘use python‘)
effect_row=cursor.execute(
"update host set host=‘192.168.56.15‘")
conn.commit()
cursor.close()
conn.close()

查看修改结果:

mysql> select * from python.host;

+---------+---------------+

| host_id | host          |

+---------+---------------+

|       1 | 192.168.56.15 |

+---------+---------------+

1 row in set (0.00 sec)

3.2 查看mysql的输出结果

import pymysql
conn = pymysql.connect(
host="192.168.56.15",port=3306,user="python",password="123456", charset=‘utf8‘)
cursor =conn.cursor()

#输出字典类型数据
#cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
effect_row=cursor.execute("update host set host=‘192.168.56.15‘ WHERE  host_id<15")
#
执行命令
cursor.execute(
"select * from host")
# 获取执行命令后输出的第一行数据
#row_1 = cursor.fetchone()
#
获取前n行数据
row_2 = cursor.fetchmany(3)
# 获取所有数据
#row_3 = cursor.fetchall()

print(row_2)
conn.commit()
cursor.close()
conn.close()

注:在fetch数据时按照顺序进行,可以使用cursor.scroll(num,mode)来移动游标位置,如:

l  cursor.scroll(1,mode=‘relative‘)  # 相对当前位置移动

l  cursor.scroll(2,mode=‘absolute‘) # 相对绝对位置移动

输出的结果默认是元组类型的数据,如果想输出字典类型数据可以使用:

cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

参考资料:

       python-mysqldb : http://www.cnblogs.com/wupeiqi/articles/5095821.html 

       pymysql : http://www.cnblogs.com/wupeiqi/articles/5713330.html  

4. redis

4.1 Redis优点

l  异常快速 : Redis是非常快的,每秒可以执行大约110000设置操作,81000/每秒的读取操作。

l  支持丰富的数据类型 : Redis支持最大多数开发人员已经知道如列表,集合,可排序集合,哈希等数据类型。

l  这使得在应用中很容易解决的各种问题,因为我们知道哪些问题处理使用哪种数据类型更好解决。

l  操作都是原子的 : 所有 Redis 的操作都是原子,从而确保当两个客户同时访问 Redis 服务器得到的是更新后的值(最新值)。

l  MultiUtility工具:Redis是一个多功能实用工具,可以在很多如:缓存,消息传递队列中使用(Redis原生支持发布/订阅),在应用程序中,如:Web应用程序会话,网站页面点击数等任何短暂的数据;

4.2 安装redis

$ wget http://download.redis.io/releases/redis-2.8.3.tar.gz

$ tar xzf redis-2.8.3.tar.gz

$ cd redis-2.8.3

$ make && make install

技术分享

4.3 使用redis

4.3.1 设置查询

[[email protected]][~]

# redis-cli

127.0.0.1:6379> keys *    #查询所有key

(empty list or set)

127.0.0.1:6379> set name liangkai    #设置key

OK

127.0.0.1:6379> keys *

1) "name"

127.0.0.1:6379> set age 22   

OK

127.0.0.1:6379> get name      #查询key

"liangkai"

127.0.0.1:6379> get age

"22"

127.0.0.1:6379> mget name age     #查询多个key

1) "liangkai"

2) "22"

127.0.0.1:6379>

set的参数:

n  ex:过期时间(秒),和setex功能一样

n  px:过期时间(毫秒),和psetex(name, time_ms, value)一样

n  nx:只有key值不存在时,设置操作才会生效,不会修改已经存在的key值,和setnx一样

n  xx:只有key值存在时,设置操作才会生效,会修改已经存在的key

127.0.0.1:6379> set name kaige ex 5

OK

127.0.0.1:6379> get name

"kaige"

127.0.0.1:6379> get name

(nil)

127.0.0.1:6379> set name kaige px 5000

OK

127.0.0.1:6379> get name

"kaige"

127.0.0.1:6379> get name

(nil)

127.0.0.1:6379>

同时设置多个key

127.0.0.1:6379> mset age 22 sex male

OK

127.0.0.1:6379> get sex

"male"

127.0.0.1:6379> get age

"22"

127.0.0.1:6379>

同时查询多个key

127.0.0.1:6379> mget age sex

1) "22"

2) "male"

127.0.0.1:6379>

getset设置新值并获取原来的值:

127.0.0.1:6379> getset age 35

"22"

127.0.0.1:6379> get age

"35"

127.0.0.1:6379>

getrange获取指定长度的value

127.0.0.1:6379> get sex

"male"

127.0.0.1:6379> getrange sex 2 4

"le"

127.0.0.1:6379> getrange sex 1 3

"ale"

127.0.0.1:6379> getrange sex 2 3

"le"

127.0.0.1:6379>

setrange修改指定长度的value

127.0.0.1:6379> setrange sex 2 kkkkk

(integer) 7

127.0.0.1:6379> get sex

"makkkkk"

127.0.0.1:6379>

setbit设置二进制位值

127.0.0.1:6379> get name       #namevalueA

"A"

127.0.0.1:6379> setbit name 7 0  

(integer) 1

127.0.0.1:6379> get name

"@"

127.0.0.1:6379>

说明:namevalue值是A,它的ascii码是65,也就是01000001setbit name 7 0 即把第7为改为0,修改后为01000000,根据ascii码表是“@”符号。

getbit获取对应的二进制位

127.0.0.1:6379> getbit name 1    #namevalue01000000

(integer) 1

127.0.0.1:6379> getbit name 0

(integer) 0

127.0.0.1:6379> getbit name 2

(integer) 0

127.0.0.1:6379>

bitcount获取key对应value的二进制中1的个数

127.0.0.1:6379> get name

"@"

127.0.0.1:6379> bitcount name

(integer) 1

127.0.0.1:6379>

总结:关于bit的作用

举例,我们可以统计实时有多少用户登录。

每个用户都有对应的id,我们可以把对应id的二进制位改为1,然后统计1的个数,即是当前在线的用户数。

127.0.0.1:6379> set name 0    #设置一个key值为0

OK

127.0.0.1:6379> bitcount name   #查看当前有21

(integer) 2

127.0.0.1:6379> setbit name 213 1   #id213的用户写一个1

(integer) 0

127.0.0.1:6379> setbit name 21000 1

(integer) 0

127.0.0.1:6379> setbit name 2100 1

(integer) 0

127.0.0.1:6379> setbit name 3002 1

(integer) 0

127.0.0.1:6379> setbit name 301 1

(integer) 0

127.0.0.1:6379> setbit name 51 1

(integer) 0

127.0.0.1:6379> bitcount name   #统计1的个数为8个,减去初始的两个,所以当前有6个用户在线。还可以根据1的位置,计算出用户的id

(integer) 8

127.0.0.1:6379>

strlen计算key对应value的字节长度

127.0.0.1:6379> strlen name

(integer) 2626

127.0.0.1:6379>

incr自增

127.0.0.1:6379> incr name

(integer) 4

127.0.0.1:6379> incr name

(integer) 5

127.0.0.1:6379> incr name

(integer) 6

127.0.0.1:6379> get name

"6"

incrbyfloat自增

127.0.0.1:6379> incrbyfloat name 1.1

"11.1"

127.0.0.1:6379> incrbyfloat name 1.12

"12.22"

decr自减

127.0.0.1:6379> set name 10

OK

127.0.0.1:6379> get name

"10"

127.0.0.1:6379> DECR name

(integer) 9

127.0.0.1:6379> DECR name

(integer) 8

append追加

127.0.0.1:6379> get name

"8"

127.0.0.1:6379> append name 56

(integer) 3

127.0.0.1:6379> get name

"856"

127.0.0.1:6379>

 





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