Python之路-python(mysql介绍和安装、pymysql、ORM sqlachemy)

Python之路-python(mysql介绍和安装、pymysql、ORMsqlachemy)

什么是数据库？

RDBMS术语

Mysql数据库

MySQL用户设置

1insertintouser(host,user,password,select_priv,insert_priv,update_priv)values('localhost','lisi',password('12345678'),'y','y','y');

1flushprivileges;

管理MySQL的命令

数值类型

日期和时间类型

字符串类型

1CREATETABLEtable_name(column_namecolumn_type);

createtablestudent(stu_idintnotnullauto_increment,namechar(32)notnull,ageintnotnull,register_datedate,primarykey(stu_id));

MySQL插入数据

1INSERTINTOtable_name(field1,field2,...fieldN)
2VALUES
3(value1,value2,...valueN);

1mysql>insertintostudent(name,age,register_date)values("zhangsan",22,"2016-10-26");
2QueryOK,1rowaffected(0.00sec)
3
4mysql>select*fromstudent;
5+--------+----------+-----+---------------+
6|stu_id|name|age|register_date|
7+--------+----------+-----+---------------+
8|1|zhangsan|22|2016-10-26|
9+--------+----------+-----+---------------+
101rowinset(0.00sec)

MySQL查询数据

1SELECTcolumn_name,column_name
2FROMtable_name
3[WHEREClause]
4[OFFSETM][LIMITN]

1mysql>select*fromstudent;
2+--------+-----------+-----+---------------+
3|stu_id|name|age|register_date|
4+--------+-----------+-----+---------------+
5|1|zhangsan|22|2016-10-26|
6|2|zhangsan1|23|2016-10-27|
7|3|zhangsan2|24|2016-10-28|
8|4|zhangsan3|25|2016-10-29|
9+--------+-----------+-----+---------------+
104rowsinset(0.00sec)
11
12方法一：
13mysql>selectnamefromstudentwherename="zhangsan2";
14+-----------+
15|name|
16+-----------+
17|zhangsan2|
18+-----------+
191rowinset(0.00sec)
20
21方法二：
22mysql>selectname,agefromstudentwherename="zhangsan2"andage=24;
23+-----------+-----+
24|name|age|
25+-----------+-----+
26|zhangsan2|24|
27+-----------+-----+
281rowinset(0.00sec)

1mysql>select*fromstudent;
2+--------+-----------+-----+---------------+
3|stu_id|name|age|register_date|
4+--------+-----------+-----+---------------+
5|1|zhangsan|22|2016-10-26|
6|2|zhangsan1|23|2016-10-27|
7|3|zhangsan2|24|2016-10-28|
8|4|zhangsan3|25|2016-10-29|
9+--------+-----------+-----+---------------+
104rowsinset(0.00sec)

1#limit相当于从表中的第几条开始查询，offset代表从前面第几条开始计算的第几条数据。（包含limit那行）
2方法一：
3mysql>select*fromstudentlimit2offset1;
4+--------+-----------+-----+---------------+
5|stu_id|name|age|register_date|
6+--------+-----------+-----+---------------+
7|2|zhangsan1|23|2016-10-27|
8|3|zhangsan2|24|2016-10-28|
9+--------+-----------+-----+---------------+
102rowsinset(0.00sec)
11
12
13#下面这个少了个offset，完全就变了。下面说明是从limit指定条开始读，后面1代表读几行。
14方法二：
15mysql>select*fromstudentlimit2,1;
16+--------+-----------+-----+---------------+
17|stu_id|name|age|register_date|
18+--------+-----------+-----+---------------+
19|3|zhangsan2|24|2016-10-28|
20+--------+-----------+-----+---------------+
211rowinset(0.00sec)

MySQLwhere子句

1SELECTfield1,field2,...fieldNFROMtable_name1,table_name2...
2[WHEREcondition1[AND[OR]]condition2.....

1mysql>select*fromstudentwhereage>24;
2+--------+-----------+-----+---------------+
3|stu_id|name|age|register_date|
4+--------+-----------+-----+---------------+
5|4|zhangsan3|25|2016-10-29|
6+--------+-----------+-----+---------------+
71rowinset(0.00sec)

MySQLUPDATE查询

1mysql>select*fromstudent;
2+--------+-----------+-----+---------------+
3|stu_id|name|age|register_date|
4+--------+-----------+-----+---------------+
5|1|zhangsan|22|2016-10-26|
6|2|zhangsan1|23|2016-10-27|
7|3|zhangsan2|24|2016-10-28|
8|4|zhangsan3|25|2016-10-29|
9+--------+-----------+-----+---------------+
104rowsinset(0.00sec)
11
12mysql>updatestudentsetage=28wherename="zhangsan3"andage="25";
13QueryOK,1rowaffected(0.00sec)
14Rowsmatched:1Changed:1Warnings:0
15
16mysql>select*fromstudent;
17+--------+-----------+-----+---------------+
18|stu_id|name|age|register_date|
19+--------+-----------+-----+---------------+
20|1|zhangsan|22|2016-10-26|
21|2|zhangsan1|23|2016-10-27|
22|3|zhangsan2|24|2016-10-28|
23|4|zhangsan3|28|2016-10-29|
24+--------+-----------+-----+---------------+
254rowsinset(0.00sec)

MySQLDELETE语句

1DELETEFROMtable_name[WHEREClause]<br><br>deletefromstudentwherestu_id=5;

1mysql>deletefromstudentwherename="zhangsan3"andage=28;
2QueryOK,1rowaffected(0.00sec)
3
4mysql>select*fromstudent;
5+--------+-----------+-----+---------------+
6|stu_id|name|age|register_date|
7+--------+-----------+-----+---------------+
8|1|zhangsan|22|2016-10-26|
9|2|zhangsan1|23|2016-10-27|
10|3|zhangsan2|24|2016-10-28|
11+--------+-----------+-----+---------------+
123rowsinset(0.00sec)

MySQLLIKE子句

1SELECTfield1,field2,...fieldNtable_name1,table_name2...
2WHEREfield1LIKEcondition1[AND[OR]]filed2='somevalue'
3
4
5select*fromstudentwherenamebinarylike"%Li";
6select*fromstudentwherenamebinarylikebinary"%Li";#只匹配大写

1mysql>select*fromstudentwherenamelike"zhang%";
2+--------+-----------+-----+---------------+
3|stu_id|name|age|register_date|
4+--------+-----------+-----+---------------+
5|1|zhangsan|22|2016-10-26|
6|2|zhangsan1|23|2016-10-27|
7|3|zhangsan2|24|2016-10-28|
8|5|zhangsan3|25|2016-10-29|
9+--------+-----------+-----+---------------+
104rowsinset(0.00sec)
11
12mysql>select*fromstudentwhereagelike"24";
13+--------+-----------+-----+---------------+
14|stu_id|name|age|register_date|
15+--------+-----------+-----+---------------+
16|3|zhangsan2|24|2016-10-28|
17+--------+-----------+-----+---------------+
181rowinset(0.00sec)

MySQL排序

1SELECTfield1,field2,...fieldNfromtable_name1,table_name2...
2ORDERBYfield1,[field2...][ASC[DESC]]
3使用ASC或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。

1mysql>select*fromstudent;
2+--------+-----------+-----+---------------+
3|stu_id|name|age|register_date|
4+--------+-----------+-----+---------------+
5|1|zhangsan|22|2016-10-26|
6|2|zhangsan1|23|2016-10-27|
7|3|zhangsan2|24|2016-10-28|
8|5|zhangsan3|25|2016-10-29|
9|6|ZHANGSAN4|26|2016-10-30|
10+--------+-----------+-----+---------------+
115rowsinset(0.00sec)
12
13mysql>selectagefromstudentorderbyageDESC;
14+-----+
15|age|
16+-----+
17|26|
18|25|
19|24|
20|23|
21|22|
22+-----+
235rowsinset(0.00sec)
24
25mysql>selectagefromstudentorderbyageasc;
26+-----+
27|age|
28+-----+
29|22|
30|23|
31|24|
32|25|
33|26|
34+-----+
355rowsinset(0.00sec)

MySQLGROUPBY语句　　

1SELECTcolumn_name,function(column_name)
2FROMtable_name
3WHEREcolumn_nameoperatorvalue
4GROUPBYcolumn_name;

mysql>select*fromstudent;
+--------+-----------+-----+---------------+
|stu_id|name|age|register_date|
+--------+-----------+-----+---------------+
|1|zhangsan|22|2016-10-26|
|2|zhangsan1|23|2016-10-27|
|3|zhangsan2|24|2016-10-28|
|5|zhangsan3|25|2016-10-29|
|6|ZHANGSAN4|26|2016-10-30|
|7|zhangsan2|24|2016-10-25|
+--------+-----------+-----+---------------+
6rowsinset(0.00sec)

#接下来我们使用GROUPBY语句将数据表按名字进行分组，并统计每个人有多少条记录：
mysql>selectname,count(*)fromstudentgroupbyname;
+-----------+----------+
|name|count(*)|
+-----------+----------+
|zhangsan|1|
|zhangsan1|1|
|zhangsan2|2|
|zhangsan3|1|
|ZHANGSAN4|1|
+-----------+----------+
5rowsinset(0.00sec)

1#使用WITHROLLUP
#我们模拟stu_id就登陆数，统计一下总登录量

2mysql>selectcoalesce(name,"总数"),sum(stu_id)assingin_conutfromstudentgroupbynamewithrollup;
3+-------------------------+--------------+
4|coalesce(name,"总数")|singin_conut|
5+-------------------------+--------------+
6|zhangsan|1|
7|zhangsan1|2|
8|zhangsan2|10|
9|zhangsan3|5|
10|ZHANGSAN4|6|
11|总数|24|
12+-------------------------+--------------+
136rowsinset(0.00sec)
14
15其中记录NULL表示所有人的登录次数。<br>
16我们可以使用coalesce来设置一个可以取代NUll的名称，coalesce语法：
17mysql>selectcoalesce(name,"总数"),sum(stu_id)assingin_conutfromstudentgroupbynamewithrollup;

MySQLALTER命令

1mysql>altertablestudentdropregister_date;
2QueryOK,6rowsaffected(0.01sec)
3Records:6Duplicates:0Warnings:0
4
5mysql>select*fromstudent;
6+--------+-----------+-----+
7|stu_id|name|age|
8+--------+-----------+-----+
9|1|zhangsan|22|
10|2|zhangsan1|23|
11|3|zhangsan2|24|
12|5|zhangsan3|25|
13|6|ZHANGSAN4|26|
14|7|zhangsan2|24|
15+--------+-----------+-----+
166rowsinset(0.00sec)

1mysql>altertablestudentaddsinginint(32)notnull;
2QueryOK,6rowsaffected(0.01sec)
3Records:6Duplicates:0Warnings:0
4
5mysql>select*fromstudent;
6+--------+-----------+-----+--------+
7|stu_id|name|age|singin|
8+--------+-----------+-----+--------+
9|1|zhangsan|22|0|
10|2|zhangsan1|23|0|
11|3|zhangsan2|24|0|
12|5|zhangsan3|25|0|
13|6|ZHANGSAN4|26|0|
14|7|zhangsan2|24|0|
15+--------+-----------+-----+--------+
166rowsinset(0.00sec)

1mysql>ALTERTABLEtestalter_tblMODIFYcCHAR(10);

1mysql>ALTERTABLEtestalter_tblCHANGEijBIGINT;
3mysql>ALTERTABLEtestalter_tblCHANGEjjINT;

ALTERTABLE对Null值和默认值的影响

1mysql>ALTERTABLEtestalter_tbl
2->MODIFYjBIGINTNOTNULLDEFAULT100;

修改表名

1mysql>ALTERTABLEtestalter_tblRENAMETOalter_tbl;

关于外键

1mysql>createtableclass(
2->idintnotnullprimarykey,
3->namechar(16));
4QueryOK,0rowsaffected(0.02sec)
5
6
7CREATETABLE`student2`(
8`id`int(11)NOTNULL,
9`name`char(16)NOTNULL,
10`class_id`int(11)NOTNULL,
11PRIMARYKEY(`id`),
12KEY`fk_class_key`(`class_id`),
13CONSTRAINT`fk_class_key`FOREIGNKEY(`class_id`)REFERENCES`class`(`id`)
14)
31此时如果class表中不存在id1,student表也插入不了，这就叫外键约束
32mysql>insertintostudent2(id,name,class_id)values(1,'alex',1);
33ERROR1452(23000):Cannotaddorupdateachildrow:aforeignkeyconstraintfails(`testdb`.`student2`,CONSTRAINT`fk_class_key`FOREIGNKEY(`class_id`)REFERENCES`class`(`id`))
34
35
36
37mysql>insertintoclass(id,name)values(1,"linux");
38QueryOK,1rowaffected(0.01sec)
39
40mysql>insertintostudent2(id,name,class_id)values(1,'alex',1);
41QueryOK,1rowaffected(0.00sec)
42
43
44＃如果有student表中跟这个class表有关联的数据，你是不能删除class表中与其关联的纪录的
45mysql>deletefromclasswhereid=1;
46ERROR1451(23000):Cannotdeleteorupdateaparentrow:aforeignkeyconstraintfails(`testdb`.`student2`,CONSTRAINT`fk_class_key`FOREIGNKEY(`class_id`)REFERENCES`class`(`id`))

MySQLNULL值处理　　

Mysql连接（leftjoin,rightjoin,innerjoin,fulljoin）

#交集
mysql>select*fromAinnerjoinBonA.id=B.id;
+----+----+
|id|id|
+----+----+
|3|3|
|4|4|
+----+----+
2rowsinset(0.00sec)

1mysql>select*fromAleftjoinBonA.id=B.id;
2+----+------+
3|id|id|
4+----+------+
5|1|NULL|
6|2|NULL|
7|3|3|
8|4|4|
9+----+------+
104rowsinset(0.00sec)
11
12mysql>select*fromBleftjoinAonB.id=A.id;
13+----+------+
14|id|id|
15+----+------+
16|3|3|
17|4|4|
18|5|NULL|
19|6|NULL|
20|7|NULL|
21|8|NULL|
22+----+------+
236rowsinset(0.00sec)

1mysql>select*fromArightjoinBonA.id=B.id;
2+------+----+
3|id|id|
4+------+----+
5|3|3|
6|4|4|
7|NULL|5|
8|NULL|6|
9|NULL|7|
10|NULL|8|
11+------+----+
126rowsinset(0.00sec)

1mysql>select*fromAleftjoinBonA.id=B.idunionselect*fromArightjoinBonA.id=B.id;
2+------+------+
3|id|id|
4+------+------+
5|1|NULL|
6|2|NULL|
7|3|3|
8|4|4|
9|NULL|5|
10|NULL|6|
11|NULL|7|
12|NULL|8|
13+------+------+
148rowsinset(0.00sec)

1mysql>showcreatetableC;
2+-------+-----------------------------------------------------------------------------------------------------+
3|Table|CreateTable|
4+-------+-----------------------------------------------------------------------------------------------------+
5|C|CREATETABLE`C`(
6`a`int(11)NOTNULL,
7PRIMARYKEY(`a`)
8)ENGINE=InnoDBDEFAULTCHARSET=utf8|
9+-------+-----------------------------------------------------------------------------------------------------+
101rowinset(0.00sec)
11
12mysql>begin;
13QueryOK,0rowsaffected(0.00sec)
14
15mysql>insertintoC(a)values(1);
16QueryOK,1rowaffected(0.00sec)
17
18mysql>select*fromC;
19+---+
20|a|
21+---+
22|1|
23+---+
241rowinset(0.00sec)
25
26mysql>rollback;
27QueryOK,0rowsaffected(0.00sec)
28
29mysql>select*fromC;
30Emptyset(0.00sec)
31
32mysql>

1CREATEINDEXindexNameONmytable(username(length));

1ALTERmytableADDINDEX[indexName]ON(username(length))

1CREATETABLEmytable(
2
3IDINTNOTNULL,
4
5usernameVARCHAR(16)NOTNULL,
6
7INDEX[indexName](username(length))
8
9);

1DROPINDEX[indexName]ONmytable;

1SHOWINDEXFROMtable_name\G

1easy_installpymysql

1importpymysql
2
3#创建连接
4conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',passwd='123',db='t1')
5#创建游标
6cursor=conn.cursor()
7
8#执行SQL，并返回收影响行数
9effect_row=cursor.execute("updatehostssethost='1.1.1.2'")
10
11#执行SQL，并返回受影响行数
12#effect_row=cursor.execute("updatehostssethost='1.1.1.2'wherenid>%s",(1,))
13
14#执行SQL，并返回受影响行数
15#effect_row=cursor.executemany("insertintohosts(host,color_id)values(%s,%s)",[("1.1.1.11",1),("1.1.1.11",2)])
16
17
18#提交，不然无法保存新建或者修改的数据
19conn.commit()
20
21#关闭游标
22cursor.close()
23#关闭连接
24conn.close()

1importpymysql
2
3#创建连接（相当于创建了一个socket连接）
4conn=pymysql.connect(host='172.16.5.237',port=3306,user='root',passwd='12345678',db='oldboy')
5
6#创建游标#实时上我们的是cursor来取数据
7cursor=conn.cursor()
8
9#执行SQL，并返回收影响行数
10effect_row=cursor.execute("select*fromA;")
11#print(effect_row)#显示表中有几行
12#print(cursor.fetchone())#取一行
13#print(cursor.fetchall())#打印表中的所有数据
14
15#执行SQL，并返回受影响行数
16#effect_row=cursor.execute("updatehostssethost='1.1.1.2'wherenid>%s",(1,))
17
18#执行SQL，并返回受影响行数
19#effect_row=cursor.executemany("insertintohosts(host,color_id)values(%s,%s)",[("1.1.1.11",1),("1.1.1.11",2)])
20
21#批量插入
22#data=[
23#(22),
24#(33),
25#(44)
26#]
27#effect_row=cursor.executemany("insertintoA(id)values(%s)",data)#批量写入
28
29#提交，不然无法保存新建或者修改的数据
30conn.commit()#默认就客气了事务，所以这里不提交数据库就没有数据
31
32#关闭游标
33cursor.close()
34#关闭连接
35conn.close()

1#!/usr/bin/envpython
2#-*-coding:utf-8-*-
3importpymysql
4
5conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',passwd='123',db='t1')
6cursor=conn.cursor()
7cursor.executemany("insertintohosts(host,color_id)values(%s,%s)",[("1.1.1.11",1),("1.1.1.11",2)])
8conn.commit()
9cursor.close()
10conn.close()
11
12#获取最新自增ID
13new_id=cursor.lastrowid

1#!/usr/bin/envpython
2#-*-coding:utf-8-*-
3importpymysql
4
5conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',passwd='123',db='t1')
6cursor=conn.cursor()
7cursor.execute("select*fromhosts")
8
9#获取第一行数据
10row_1=cursor.fetchone()
11
12#获取前n行数据
13#row_2=cursor.fetchmany(3)
14#获取所有数据
15#row_3=cursor.fetchall()
16
17conn.commit()
18cursor.close()
19conn.close()

1importpymysql
2
3conn=pymysql.connect(host='127.0.0.1',port=3306,user='root',passwd='123',db='t1')
4
5#游标设置为字典类型
6cursor=conn.cursor(cursor=pymysql.cursors.DictCursor)
7r=cursor.execute("callp1()")
8
9result=cursor.fetchone()
10
11conn.commit()
12cursor.close()
13conn.close()

1MySQL-Python
2mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>
3
4pymysql
5mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]
6
7MySQL-Connector
8mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>
9
10cx_Oracle
11oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]
12
13更多详见：http://docs.sqlalchemy.org/en/latest/dialects/index.html

1easy_installsqlalchemy

1importsqlalchemy
2fromsqlalchemyimportcreate_engine
3fromsqlalchemy.ext.declarativeimportdeclarative_base
4fromsqlalchemyimportColumn,Integer,String
5
6engine=create_engine("mysql+pymysql://root:12345678@172.16.5.237/oldboy",
7encoding='utf-8',echo=True)
8
9
10Base=declarative_base()#生成orm基类
11
12classUser(Base):
13__tablename__='user'#表名
14id=Column(Integer,primary_key=True)
15name=Column(String(32))
16password=Column(String(64))
17
18Base.metadata.create_all(engine)#创建表结构

1fromsqlalchemyimportTable,MetaData,Column,Integer,String,ForeignKey
2fromsqlalchemy.ormimportmapper
3
4metadata=MetaData()
5
6user=Table('user',metadata,
7Column('id',Integer,primary_key=True),
8Column('name',String(50)),
9Column('fullname',String(50)),
10Column('password',String(12))
11)
12
13classUser(object):
14def__init__(self,name,fullname,password):
15self.name=name
16self.fullname=fullname
17self.password=password
18
19mapper(User,user)#thetablemetadataiscreatedseparatelywiththeTableconstruct,thenassociatedwiththeUserclassviathemapper()function

1importsqlalchemy
2fromsqlalchemyimportcreate_engine
3fromsqlalchemy.ext.declarativeimportdeclarative_base
4fromsqlalchemyimportColumn,Integer,String
5fromsqlalchemy.ormimportsessionmaker
6
7engine=create_engine("mysql+pymysql://root:12345678@172.16.5.237/oldboy",
8encoding='utf-8',echo=True)
9
10
11Base=declarative_base()#生成orm基类
12
13classUser(Base):
14__tablename__='user'#表名
15id=Column(Integer,primary_key=True)
16name=Column(String(32))
17password=Column(String(64))
18
19Session_class=sessionmaker(bind=engine)#创建与数据库的会话sessionclass,注意,这里返回给session的是个class,不是实例
20Session=Session_class()#生成session实例
21
22
23user_obj=User(name="zhangsan",password="12345678")#生成你要创建的数据对象
24print(user_obj.name,user_obj.id)#此时还没创建对象呢，不信你打印一下id发现还是None
25
26Session.add(user_obj)#把要创建的数据对象添加到这个session里，一会统一创建
27print(user_obj.name,user_obj.id)#此时也依然还没创建
28
29Session.commit()#现此才统一提交，创建数据
30
31
32Base.metadata.create_all(engine)#创建表结构

1importsqlalchemy
2fromsqlalchemyimportcreate_engine
3fromsqlalchemy.ext.declarativeimportdeclarative_base
4fromsqlalchemyimportColumn,Integer,String
5fromsqlalchemy.ormimportsessionmaker
6
7engine=create_engine("mysql+pymysql://root:12345678@172.16.5.237/oldboy",
8encoding='utf-8')#echo=True这里去掉这里
9
10
11Base=declarative_base()#生成orm基类
12
13classUser(Base):
14__tablename__='user'#表名
15id=Column(Integer,primary_key=True)
16name=Column(String(32))
17password=Column(String(64))
18
19Session_class=sessionmaker(bind=engine)#创建与数据库的会话sessionclass,注意,这里返回给session的是个class,不是实例
20Session=Session_class()#生成session实例
21
22data=Session.query(User).filter_by(name="zhangsan").all()#.all数所有
23print(data[0].name,data[0].password)#因为这里取出的是一个列表，所以就得这么取
24
25Session.commit()#现此才统一提交，创建数据
26
27
28Base.metadata.create_all(engine)#创建表结构

1importsqlalchemy
2fromsqlalchemyimportcreate_engine
3fromsqlalchemy.ext.declarativeimportdeclarative_base
4fromsqlalchemyimportColumn,Integer,String
5fromsqlalchemy.ormimportsessionmaker
6
7engine=create_engine("mysql+pymysql://root:12345678@172.16.5.237/oldboy",
8encoding='utf-8')#echo=True这里去掉这里
9
10
11Base=declarative_base()#生成orm基类
12
13
14classUser(Base):
15__tablename__='user'#表名
16id=Column(Integer,primary_key=True)
17name=Column(String(32))
18password=Column(String(64))
19
20def__repr__(self):
21return"<name=%s,password=%s)>"%(self.name,self.password)
22
23Session_class=sessionmaker(bind=engine)#创建与数据库的会话sessionclass,注意,这里返回给session的是个class,不是实例
24Session=Session_class()#生成session实例
25
26data=Session.query(User).filter_by(name="zhangsan").all()#.all()数所有
27print(data)#
28
29Session.commit()#现此才统一提交，创建数据
30
31
32Base.metadata.create_all(engine)#创建表结构

1importsqlalchemy
2fromsqlalchemyimportcreate_engine
3fromsqlalchemy.ext.declarativeimportdeclarative_base
4fromsqlalchemyimportColumn,Integer,String
5fromsqlalchemy.ormimportsessionmaker
6
7engine=create_engine("mysql+pymysql://root:12345678@172.16.5.237/oldboy",
8encoding='utf-8')#echo=True这里去掉这里
9
10
11Base=declarative_base()#生成orm基类
12
13
14classUser(Base):
15__tablename__='user'#表名
16id=Column(Integer,primary_key=True)
17name=Column(String(32))
18password=Column(String(64))
19
20def__repr__(self):
21return"<name=%s,password=%s)>"%(self.name,self.password)
22
23Session_class=sessionmaker(bind=engine)#创建与数据库的会话sessionclass,注意,这里返回给session的是个class,不是实例
24Session=Session_class()#生成session实例
25
26data=Session.query(User).filter_by(name="zhangsan").first()#.all()数所有
27data.name="lisi"
28print(data)#
29
30Session.commit()#现此才统一提交，创建数据
31
32
33Base.metadata.create_all(engine)#创建表结构

1importsqlalchemy
2fromsqlalchemyimportcreate_engine
3fromsqlalchemy.ext.declarativeimportdeclarative_base
4fromsqlalchemyimportColumn,Integer,String
5fromsqlalchemy.ormimportsessionmaker
6
7engine=create_engine("mysql+pymysql://root:12345678@172.16.5.237/oldboy",
8encoding='utf-8')#echo=True这里去掉这里
9
10
11Base=declarative_base()#生成orm基类
12
13
14classUser(Base):
15__tablename__='user'#表名
16id=Column(Integer,primary_key=True)
17name=Column(String(32))
18password=Column(String(64))
19
20def__repr__(self):
21return"<name=%s,password=%s)>"%(self.name,self.password)
22
23Session_class=sessionmaker(bind=engine)#创建与数据库的会话sessionclass,注意,这里返回给session的是个class,不是实例
24Session=Session_class()#生成session实例
25
26fake_user=User(name="hehe",password='12345678')
27Session.add(fake_user)
28
29print(Session.query(User).filter(User.name.in_(['hehe'])).all())#这时看session里有你刚添加和修改的数据
30
31Session.rollback()#回滚一下
32print("rollback后")
33
34print(Session.query(User).filter(User.name.in_(['hehe'])).all())#再看看有没有数据了
35
36
37#Session.commit()#现此才统一提交，创建数据
38#Base.metadata.create_all(engine)#创建表结构

1print(Session.query(User.name,User.id).all())

1objs=Session.query(User).filter(User.id>0).filter(User.id<7).all()

1Session.query(User).filter(User.name.like("Ra%")).count()

1fromsqlalchemyimportfunc
2print(Session.query(func.count(User.name),User.name).group_by(User.name).all())

1__author__='Administrator'
2
3importsqlalchemy
4fromsqlalchemyimportcreate_engine
5fromsqlalchemy.ext.declarativeimportdeclarative_base
6fromsqlalchemyimportColumn,Enum,Integer,String,DATE,ForeignKey
7fromsqlalchemy.ormimportsessionmaker,relationship
8
9engine=create_engine("mysql+pymysql://root:12345678@172.16.5.238/oldboydb",
10encoding='utf-8')#echo=True这里去掉这里
11Base=declarative_base()#生成orm基类
12
13classStudent(Base):
14__tablename__="student"
15id=Column(Integer,primary_key=True)
16name=Column(String(32),nullable=False)
17register_date=Column(DATE,nullable=False)
18
19def__repr__(self):
20return"<%sname:%s>"%(self.id,self.name)
21
22classStudy_record(Base):
23__tablename__="study_record"
24id=Column(Integer,primary_key=True)
25day=Column(Integer,nullable=False)
26status=Column(String(32),nullable=False)
27stu_id=Column(Integer,ForeignKey("student.id"))
28
29student=relationship("Student",backref="my_study_record")#这个是两个orm在内存中将两个建立表的类关联起来。
30
31def__repr__(self):
32return"<%sday:%sstatus:%s>"%(self.student.name,self.day,self.status)
33
34Base.metadata.create_all(engine)#创建表结构
35
36
37Session_class=sessionmaker(bind=engine)#创建与数据库的会话sessionclass
38Session=Session_class()#生成session实例
39
40#s1=Student(name="zhangsan1",register_date="2016-10-21")#给student表中插入数据
41#s2=Student(name="zhangsan2",register_date="2016-10-22")
42#s3=Student(name="zhangsan3",register_date="2016-10-23")
43#s4=Student(name="zhangsan4",register_date="2016-10-24")
44#
45#study_obj1=Study_record(day=1,status="YES",stu_id=1)给study_record表中插入数据
46#study_obj2=Study_record(day=2,status="NO",stu_id=1)
47#study_obj3=Study_record(day=3,status="YES",stu_id=1)
48#study_obj4=Study_record(day=4,status="YES",stu_id=2)
49#
50#Session.add_all([s1,s2,s3,s4,study_obj1,study_obj2,study_obj3,study_obj4])
51
52#stu_obj=Session.query(Student).filter(Student.name=="zhangsan1").first()
53#print(stu_obj.my_study_record)#通过查询Student这个类查询外键zhangsan1的study_record表中的数据
54
55stu_obj=Session.query(Study_record).filter(Study_record.stu_id=="1").all()
56print(stu_obj)#使用study_record表中的的stu_id反查所有等于1的信息（这里就将两个表的数据统一查询出来了）
57
58
59Session.commit()

1#需求：一个人的名字可能关联的是两个地址，或者更多。我们在customer表中存id和姓名。在address表中存地址
2
3fromsqlalchemyimportInteger,ForeignKey,String,Column
4fromsqlalchemy.ext.declarativeimportdeclarative_base
5fromsqlalchemy.ormimportrelationship
6fromsqlalchemyimportcreate_engine
7
8Base=declarative_base()#生成orm基类
9
10
11classCustomer(Base):#创建表结构customer表
12__tablename__='customer'
13id=Column(Integer,primary_key=True)
14name=Column(String(64))
15
16billing_address_id=Column(Integer,ForeignKey("address.id"))#下账单的地址
17shipping_address_id=Column(Integer,ForeignKey("address.id"))#收货的地址
18
19billing_address=relationship("Address",foreign_keys=[billing_address_id])
20shipping_address=relationship("Address",foreign_keys=[shipping_address_id])
21
22
23classAddress(Base):#创建address表
24__tablename__='address'
25id=Column(Integer,primary_key=True)
26street=Column(String(64))
27city=Column(String(64))
28state=Column(String(64))
29
30
31def__repr__(self):
32returnself.street
33
34engine=create_engine("mysql+pymysql://root:12345678@172.16.5.238/oldboydb",
35encoding='utf-8')
36
37#Base.metadata.create_all(engine)#创建表结构

1fromday12.pymysql_SQLAlchemyimportorm_many_fk
2fromsqlalchemy.ormimportsessionmaker
3
4Session_class=sessionmaker(bind=orm_many_fk.engine)#创建与数据库的会话sessionclass,注意,这里返回给session的是个class,不是实例
5session=Session_class()#生成session实例#cursor
6#
7#addr1=orm_many_fk.Address(street="Tiantongyuan",city="ChangPing",state="BJ")
8#addr2=orm_many_fk.Address(street="Wudaokou",city="Haidian",state="BJ")
9#addr3=orm_many_fk.Address(street="Yanjiao",city="LangFang",state="HB")
10#
11#session.add_all([addr1,addr2,addr3])
12#c1=orm_many_fk.Customer(name="Alex",billing_address=addr1,shipping_address=addr2)
13#c2=orm_many_fk.Customer(name="Jack",billing_address=addr3,shipping_address=addr3)
14#
15#session.add_all([c1,c2])
16
17obj=session.query(orm_many_fk.Customer).filter(orm_many_fk.Customer.name=="jack").first()
18print(obj.name,obj.billing_address,obj.shipping_address)
19
20session.commit()

1fromsqlalchemyimportTable,Column,Integer,String,DATE,ForeignKey
2fromsqlalchemy.ormimportrelationship
3fromsqlalchemy.ext.declarativeimportdeclarative_base
4fromsqlalchemyimportcreate_engine
5fromsqlalchemy.ormimportsessionmaker
6
7
8Base=declarative_base()
9
10
11book_m2m_author=Table('book_m2m_author',Base.metadata,
12Column('book_id',Integer,ForeignKey('books.id')),
13Column('author_id',Integer,ForeignKey('authors.id')),
14)
15
16classBook(Base):
17__tablename__='books'
18id=Column(Integer,primary_key=True)
19name=Column(String(64))
20pub_date=Column(DATE)
21authors=relationship('Author',secondary=book_m2m_author,backref='books')
22
23def__repr__(self):
24returnself.name
25
26classAuthor(Base):
27__tablename__='authors'
28id=Column(Integer,primary_key=True)
29name=Column(String(32))
30
31def__repr__(self):
32returnself.name
33
34engine=create_engine("mysql+pymysql://root:12345678@172.16.5.238/oldboydb?charset=utf8",
35)
36
37Base.metadata.create_all(engine)#创建表结构

1fromday12.pymysql_SQLAlchemyimportorm_m2m
2fromsqlalchemy.ormimportsessionmaker
3
4Session_class=sessionmaker(bind=orm_m2m.engine)#创建与数据库的会话sessionclass,注意,这里返回给session的是个class,不是实例
5session=Session_class()#生成session实例#cursor
6
7
8#b1=orm_m2m.Book(name="learnpythonwithAlex",pub_date="2014-05-2")
9#b2=orm_m2m.Book(name="learnZhangbilitywithAlex",pub_date="2015-05-2")
10#b3=orm_m2m.Book(name="跟Alex去泰国",pub_date="2016-05-2")
11
12#a1=orm_m2m.Author(name="Alex")
13#a2=orm_m2m.Author(name="Jack")
14#a3=orm_m2m.Author(name="Rain")
15#
16#b1.authors=[a1,a3]
17#b3.authors=[a1,a2,a3]
18
19#session.add_all([b3,])
20
21author_obj=session.query(orm_m2m.Author).filter(orm_m2m.Author.name=="Alex").first()
22print(author_obj.books)
23#book_obj=session.query(orm_m2m.Book).filter(orm_m2m.Book.id==2).first()
24#book_obj.authors.remove(author_obj)
25#session.commit()