一、复习
1.1.数据库操作（mysql）
1.1.1.创建数据库
语法：
create database db;
示例：
创建test数据库
create database test;
1.1.2.权限授权
语法：grant all privileges on *.* to '用户名'@'%' identified by '登录密码';
示例：
创建admin(密码为123456)的用户，并授权，带可授权权限的
grant all privileges on *.* to 'admin'@'%' identified by '123456' with grant option;
1.1.3.创建表
语法:create table tb(字段1 类型,字段2 类型,....)
示例：
创建student表，包含id(int类型），name(varchar)，age(int类型)，sex（枚举）
create table student(id int not null auto_increment primary_key,name varchar(50),age int,sex enum('F','G'));
1.1.3.增加数据
语法：insert into tb(字段1，字段2，......) values(值1，值2，......)
示例：
向student表中插入数据
insert into student(name,age,sex) values("test01",15,"F"),("test02",26,"G"),("test03",24,"F"),("zhangsan",32,"G"),("lisi",45,"F");
1.1.4.查询数据
语法：select 字段1，字段2 from 表名 where 条件1 and（or） 条件2
示例：
查出name包含test的name，age，sex信息
select * from student where name like '%test%'
1.1.5.修改数据
语法：update 表名 set 字段名=新值 where 条件1;
示例：
将zhangsan的年龄修改为22
update student set age=22 where name='zhangsan';
1.1.6.删除数据
语法：
delete from 表名 where 条件1;
示例：
删除name为test03数据
delete from student where name='test03';
1.1.7.删除表
语法：drop table 表名;
示例：
删除student表
drop table student;
1.1.8.join(联合查询)
语法：select a.字段1，b.字段2 from 表1 a join 表2 b on a.id=b.id
示例：
select a.name teacher_name,b.name student_name from teacher a join relation_table c on a.id=c.teacher_id join student b on b.id = c.student_id;
1.1.9.创建索引
语法：creat index idx_库名_表名_列名1_列名2 on 表名(列名1，列名2);
示例
创建student中的name,sex索引
create index idx_test_student_name_sex on student(name,sex);
1.1.10.查看执行的SQL是走索引
语法：
explain sql语句;
示例：
explain select * from student;
1.2.python连接数据库
python2 默认使用的MySQLDB
python3使用的pymysql ，pymysql需要安装 pip install pymysql
示例：
第一步：创建数据库连接和游标，游标用于执行SQL
import pymysql
#创建数据库连接
conn=pymysql.connect(host="127.0.0.1",port=3306,user="root",password="123456",db="test")
#创建游标
cursor=conn.cursor()
第二步：执行SQL
定义sql
sql = "select * from student"
# 执行
cursor.execute(sql)
# 取所有的结果,取结果之前，一定要先执行sql
cursor.fetchall()
# 取一个结果
# cursor.fetchone()
# 取10行数据
# cursor.fetchmany(size=10)
第三步：关闭游标和连接
#关闭游标
cursor.close()
#关闭连接
conn.close()
1.3.SQLAlchemy
1.3.1.创建表
示例创建teacher表
#创建引擎
#mysql+pymysql://数据库登录名:数据库登录密码@数据库服务器IP/所使用的数据库名 +pymysql：python3专用
engine=create_engine('mysql+pymysql://root:[email protected]/test')
#使用元数据MetaData获取引擎
metadata=MetaData(engine)
#创建表模型 Table第一个参数为要创建表的表名，第二个参数为连接数据库的元数据，第三个以后的参数为创建表的字段
teacher=Table('teacher',metadata,
Column("id",Integer,primary_key=True,autoincrement=True),
Column("name",String(50)),
Column("sex",Enum("F","G")),
Column("course",String(100))
)
#执行建表操作
metadata.create_all()
1.3.2.插入数据
示例from sqlalchemy import create_engine, Column, String, Enum
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
engine=create_engine('mysql+pymysql://root:[email protected]/test')
#创建session工厂
DBSession = sessionmaker(bind=engine)
#创建一个session
session=DBSession()
base=declarative_base()
#创建对表teacher的模型
class Teacher(base):
__tablename__='teacher'
name=Column(String(50))
sex=Column(Enum('F','G'))
course=Column(String(100))
#引入模型，实例化数据
teacher1=Teacher("chen teacher","G","yuwen")
teacher2=Teacher("wang teacher","F","shuxue")
teacher3=Teacher("liu teacher","G","yingyu")
teacher4=Teacher("pan teacher","F","wuli")
teacher5=Teacher("xiang teacher","G","huaxue")
#向表中插入一条数据
session.add(teacher1)
#向表中插入多条数据
session.add_all([teacher2,teacher3,teacher4,teacher5])
#提交操作
session.commit()
#关闭session
session.close()
1.3.3.查询数据
1.过滤filter()示例
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base=declarative_base()
class Student(base):
__tablename__='student'
id=Column(Integer,primary_key=True)
name=Column(String(50))
age=Column(Integer)
sex=Column(Enum('F','G'))
def select(session):
result = session.query(Student). filter(Student.name == 'lisi').one()
print(result.name, result.age, result.sex)
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
#查询
select(session)
if __name__ == '__main__':
main()
2.过滤filter_by()
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base=declarative_base()
class Student(base):
__tablename__='student'
id=Column(Integer,primary_key=True)
name=Column(String(50))
age=Column(Integer)
sex=Column(Enum('F','G'))
def select(session):
result = session.query(Student). filter_by(name = 'lisi').all()
print(result.name, result.age, result.sex)
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
#查询
select(session)
if __name__ == '__main__':
main()
3.filter()和filter_by()区别
filter:可以使用使用< > ==等，但条件格式必须为：表.列，不支持组合查询
filter_by():可以直接写列，不支持 < >，支持组合查询
4.模糊查询
示例
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base=declarative_base()
class Student(base):
__tablename__='student'
id=Column(Integer,primary_key=True)
name=Column(String(50))
age=Column(Integer)
sex=Column(Enum('F','G'))
def select(session):
result = session.query(Student) .filter(Student.name.like('test%'))
for i in result:
print(i.id,i.name,i.age,i.sex)
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
#查询
select(session)
if __name__ == '__main__':
main()
4.获取数据的两种方法one() 和 all()
one()返回的结果是元组tuple()
all()返回的结果是list,list里面包含若干个元组tuple
1.3.4.更新数据
更新的流程为：1.先查出来
2.更新一个类所对应的属性值
3.提交
示例
将id为2的name修改为updatename
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base = declarative_base()
class Student(base):
__tablename__ = 'student'
id = Column(Integer, primary_key=True)
name = Column(String(50))
age = Column(Integer)
sex = Column(Enum('F', 'G'))
def update(session):
result = session.query(Student).filter(Student.id == 2).one()
result.name="updatename"
session.commit()
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
# 更新
update(session)
if __name__ == '__main__':
main()
1.3.5.删除数据
删除数据流程：1.先查询
2.再直接调用delete()
3.提交
示例
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base = declarative_base()
class Student(base):
__tablename__ = 'student'
id = Column(Integer, primary_key=True)
name = Column(String(50))
age = Column(Integer)
sex = Column(Enum('F', 'G'))
def delete(session):
session.query(Student).filter(Student.id == 5) .delete()
session.commit()
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
# 更新
delete(session)
if __name__ == '__main__':
main()
1.3.6.统计、分组、排序
1.3.6.1 统计count
示例统计年龄为22的人数
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base=declarative_base()
class Student(base):
__tablename__='student'
id=Column(Integer,primary_key=True)
name=Column(String(50))
age=Column(Integer)
sex=Column(Enum('F','G'))
def select(session):
number = session.query(Student).filter(Student.age==22).count()
print(number)
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
#查询
select(session)
if __name__ == '__main__':
main()
1.3.6.2. 分组group_by
示例按年龄分组
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base=declarative_base()
class Student(base):
__tablename__='student'
id=Column(Integer,primary_key=True)
name=Column(String(50))
age=Column(Integer)
sex=Column(Enum('F','G'))
def select(session):
result = session.query(Student).group_by(Student.age).all()
for i in result:
print(i.id,i.name,i.age,i.sex)
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
#查询
select(session)
if __name__ == '__main__':
main()
结果：
1.3.6.3. 排序order_by
示例1：按年龄排序（默认为升序排序）
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base=declarative_base()
class Student(base):
__tablename__='student'
id=Column(Integer,primary_key=True)
name=Column(String(50))
age=Column(Integer)
sex=Column(Enum('F','G'))
def orderBy(session):
result = session.query(Student). order_by(Student.age).all()
for i in result:
print(i.id,i.name,i.age,i.sex)
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
#查询
orderBy(session)
if __name__ == '__main__':
main()
结果
示例2：
按年龄排序（默认为升序排序）
from sqlalchemy import create_engine, Column, String, Enum, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
base=declarative_base()
class Student(base):
__tablename__='student'
id=Column(Integer,primary_key=True)
name=Column(String(50))
age=Column(Integer)
sex=Column(Enum('F','G'))
def orderBy(session):
result = session.query(Student). order_by(Student.age.desc()).all()
for i in result:
print(i.id,i.name,i.age,i.sex)
def main():
engine = create_engine('mysql+pymysql://root:[email protected]/test')
# 创建session工厂
DBSession = sessionmaker(bind=engine)
# 创建一个session
session = DBSession()
#查询
orderBy(session)
if __name__ == '__main__':
main()
结果：
