标签：err user span 展示 params model == ocs cts
SQLAlchemy是一个基于Python实现的ORM框架。该框架建立在 DB API之上，使用关系对象映射进行数据库操作，简言之便是：将类和对象转换成SQL，然后使用数据API执行SQL并获取执行结果。
安装
pip3 install sqlalchemy
SQLAlchemy本身无法操作数据库，其必须以来pymsql等第三方插件，Dialect用于和数据API进行交流，根据配置文件的不同调用不同的数据库API，从而实现对数据库的操作，如：
MySQL-Python mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname> pymysql mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>] MySQL-Connector mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname> cx_Oracle oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...] 更多：http://docs.sqlalchemy.org/en/latest/dialects/index.html
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine engine = create_engine( "mysql+pymysql://root:123@127.0.0.1:3306/t1?charset=utf8", max_overflow=5 # 超过连接池大小外最多创建的连接 pool_siez = 5 # 连接池大小 pool_timeout = 30 # 池中没有线程最多等待的时间，否则报错， pool_recycle = 1 # 多久之后对线程池中的线程进行一次连接的回收 ) Base = declarative_base() # 创建单表 class Users(Base): __tablename__ = ‘users‘ id = Column(Integer, primary_key=True) name = Column(String(32)) extra = Column(String(16)) __table_args__ = ( UniqueConstraint(‘id‘, ‘name‘, name=‘uix_id_name‘), Index(‘ix_id_name‘, ‘name‘, ‘extra‘), ) # 一对多 class Favor(Base): __tablename__ = ‘favor‘ nid = Column(Integer, primary_key=True) caption = Column(String(50), default=‘red‘, unique=True) class Person(Base): __tablename__ = ‘person‘ nid = Column(Integer, primary_key=True) name = Column(String(32), index=True, nullable=True) favor_id = Column(Integer, ForeignKey("favor.nid")) # 多对多 class Group(Base): __tablename__ = ‘group‘ id = Column(Integer, primary_key=True) name = Column(String(64), unique=True, nullable=False) port = Column(Integer, default=22) class Server(Base): __tablename__ = ‘server‘ id = Column(Integer, primary_key=True, autoincrement=True) hostname = Column(String(64), unique=True, nullable=False) class ServerToGroup(Base): __tablename__ = ‘servertogroup‘ nid = Column(Integer, primary_key=True, autoincrement=True) server_id = Column(Integer, ForeignKey(‘server.id‘)) group_id = Column(Integer, ForeignKey(‘group.id‘)) # 初始化数据库 def init_db(): Base.metadata.create_all(engine) def drop_db(): Base.metadata.drop_all(engine)
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) Base = declarative_base() # 创建单表 class Users(Base): __tablename__ = ‘users‘ id = Column(Integer, primary_key=True) name = Column(String(32)) extra = Column(String(16)) __table_args__ = ( UniqueConstraint(‘id‘, ‘name‘, name=‘uix_id_name‘), Index(‘ix_id_name‘, ‘name‘, ‘extra‘), ) def __repr__(self): return "%s-%s" %(self.id, self.name) # 一对多 class Favor(Base): __tablename__ = ‘favor‘ nid = Column(Integer, primary_key=True) caption = Column(String(50), default=‘red‘, unique=True) def __repr__(self): return "%s-%s" %(self.nid, self.caption) class Person(Base): __tablename__ = ‘person‘ nid = Column(Integer, primary_key=True) name = Column(String(32), index=True, nullable=True) favor_id = Column(Integer, ForeignKey("favor.nid")) # 与生成表结构无关，仅用于查询方便 favor = relationship("Favor", backref=‘pers‘) # 多对多 class ServerToGroup(Base): __tablename__ = ‘servertogroup‘ nid = Column(Integer, primary_key=True, autoincrement=True) server_id = Column(Integer, ForeignKey(‘server.id‘)) group_id = Column(Integer, ForeignKey(‘group.id‘)) group = relationship("Group", backref=‘s2g‘) server = relationship("Server", backref=‘s2g‘) class Group(Base): __tablename__ = ‘group‘ id = Column(Integer, primary_key=True) name = Column(String(64), unique=True, nullable=False) port = Column(Integer, default=22) # group = relationship(‘Group‘,secondary=ServerToGroup,backref=‘host_list‘) class Server(Base): __tablename__ = ‘server‘ id = Column(Integer, primary_key=True, autoincrement=True) hostname = Column(String(64), unique=True, nullable=False) def init_db(): """创建所有定义的表到数据库中""" Base.metadata.create_all(engine) def drop_db(): """从数据库中删除所有定义的表""" Base.metadata.drop_all(engine) # 执行创建表 #init_db() # 创建会话实例对象 Session = sessionmaker(bind=engine) session = Session()
obj = Users(name="alex0", extra=‘sb‘) session.add(obj) session.add_all([ Users(name="alex1", extra=‘sb‘), Users(name="alex2", extra=‘sb‘), ]) session.commit() # 创建一个名称叫：IT部门， 再在该部门添加一个员工：田硕 方式一 d1 = Depart(title=‘IT‘) session.add(d1) session.commit() u1 = User(name=‘田硕‘,depart_id=d1.id) session.add(u1) session.commit() 方式二 u1 = User(name=‘田硕‘,dp=Depart(title=‘IT‘) session.add(u1) session.commit() # 创建一个叫财务的部门，再在部门添加多个员工 d1 = Depart(title=‘财务‘) d1.pers = [Users(name=‘harry‘, Users(name=‘jerry‘),] session.add(d1) # 创建一个课程，创建2学生。两个学生选新创建的课程 obj = ourse(title=‘英语‘) obj.student_list = [Student(name=‘harry‘),Student(‘sam‘)]
session.query(Users).filter(Users.id > 2).delete()
session.commit()
结果集内看到的是对象 、还是数据
? query(类名) 返回的就是对象
? query(类名.字段名) 返回的就是含有数据的元组对象
# 所有数据，且结果集中是一个一个的对象 # 结果 [obj1, obj2, obj3] ret = session.query(Users).all() # 指定字段查询，返回所有的数据，是一个列表，列表内是一个一个的元组 # 结果 [(‘yangge‘, ‘18‘), (‘qiangge‘, ‘19‘), (‘shark‘, ‘23‘)] ret = session.query(Users.name, Users.extra).all() #可以使用 label() 给每个列名起别名 for row in session.query(Teacher.name.label(‘t_name‘)).all(): print(row.t_name) filter_by() 接收的是关键字参数 filter() 允许使用 python 的比较或关系运算符，实现更灵活的查询 ret = session.query(Users).filter_by(name=‘alex‘).all() ret = session.query(Users).filter_by(name=‘alex‘).first() ret = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name=‘fred‘).order_by(User.id).all() ret = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name=‘ed‘).all()
session.query(Users).filter(Users.id > 2).update({"name" : "099"})
session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)
#不同步，数据的更新在 commit 之后
session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")
session.commit()
# 条件 ret = session.query(Users).filter_by(name=‘alex‘).all() # 相等 ret = session.query(Users).filter(Users.id > 1, Users.name == ‘eric‘).all() ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == ‘eric‘).all() ret = session.query(Users).filter(Users.id.in_([1,3,4])).all() # in 包含 ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all() # not in ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name=‘eric‘))).all() # IS NOT NULL query.filter(Teacher.name != None).all() # 或者 query.filter(Teacher.name.isnot(None)).all() from sqlalchemy import and_, or_ ＃AND过滤 ret = session.query(Users).filter(and_(Users.id > 3, Users.name == ‘eric‘)).all() # OR 过滤 ret = session.query(Users).filter(or_(Users.id < 2, Users.name == ‘eric‘)).all() # id 等于2或者name=eric ret = session.query(Users).filter( or_( Users.id < 2, and_(Users.name == ‘eric‘, Users.id > 3), Users.extra != "" )).all() # AND 和 OR 的综合使用 query.filter( or_( Teacher.id <= 2, and_(Teacher.name == ‘shark‘, Teacher.id > 3) )).all() # 通配符 ret = session.query(Users).filter(Users.name.like(‘e%‘)).all() ret = session.query(Users).filter(~Users.name.like(‘e%‘)).all()
# order by 排序 ret = session.query(Users).order_by(Users.name.desc()).all() ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all() # 正序 session.query(Teacher).order_by(Teacher.name).all() # 倒序 session.query(Teacher).order_by(Teacher.name.desc()).all() # 先按名字排序，假如有相同的再安装 id 排序 session.query(Teacher).order_by(Teacher.name, Teacher.id.desc()).all()
from sqlalchemy.sql import func ret = session.query(Users).group_by(Users.extra).all() ret = session.query( func.max(Users.id), func.sum(Users.id), func.min(Users.id)).group_by(Users.name).all() ret = session.query( func.max(Users.id), func.sum(Users.id), func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()
ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all() ret = session.query(Person).join(Favor).all() # isouter=True相当于left join ret = session.query(Person).join(Favor, isouter=True).all() ret = session.query(Users,Depart).join(Depart,Users.depart_id == Depart.id).all() # 多对多连表 ret = session.query(Student2Course.id, Student.name).join(Student, Student2Course.student_id==student.id).join(Course,Student2Course.course_id==Course.id).order_by(Student2Course.id.asc()) for row in ret: # 多对多反向查询 # 查找harry选有的课 obj = session.query(Studnet).filter(Student.name==‘harry‘).first() for item in obj.course_list print(item.title) # 查找选了生物课的所有人 obj = session.query(Course).filter(Course.title==‘生物‘).first() for item in obj.student_list: print(item.name)
# 分组统计查询 from sqlalchemy.sql import func # 统计表中所有的数据 session.query(func.count(‘*‘)).select_from(Teacher).first() # 以年龄分组，并统计每组的数据数量 session.query(func.count(Teacher.age),Teacher.age.group_by(Teacher.age).all() # 以年龄为分组，并统计每组的最大/最小 id 号，年龄总和/平均值， session.query( func.max(Teacher.id), func.min(Teacher.id), func.sum(Teacher.age), func.avg(Teacher.age), Teacher.id ).group_by(Teacher.age).all() # 从分组的数据中再查找需要的数据 session.query( func.max(Teacher.id), func.min(Teacher.age), func.sum(Teacher.age), func.avg(Teacher.age), Teacher.id ).group_by(Teacher.age).having(func.min(Teacher.id) > 2).all()
# 嵌套，从最内层的查询结果中再查询想要的数据 session.query(Teacher).filter( Teacher.id.in_( session.query(Teacher.id).filter_by(name=‘yangge‘))).all()
将两个查询结果结合到一起
# 组合 用一条数据将两个表中的要查询的数据组合在一张表里展示出来 q1 = session.query(Teacher.name).filter(Teacher.id > 2) q2 = session.query(Student.name).filter(Student.id < 2) ## 去重 ret = q1.union(q2).all() ## 不去重 q1 = session.query(Teacher.name).filter(Teacher.id > 2) q2 = session.query(Student.name).filter(Student.id < 2) ret = q1.union_all(q2).all()
方式一：
import time import threading import sqlalchemy from sqlalchemy import create_engine from sqlalchemy.engine.base import Engine engine = create_engine( "mysql+pymysql://root:123@127.0.0.1:3306/t1?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间，否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收（重置） ) def task(arg): conn = engine.raw_connection() cursor = conn.cursor() cursor.execute( "select * from t1" ) result = cursor.fetchall() cursor.close() conn.close() for i in range(20): t = threading.Thread(target=task, args=(i,)) t.start()
方式二：
import time import threading import sqlalchemy from sqlalchemy import create_engine from sqlalchemy.engine.base import Engine from sqlalchemy.engine.result import ResultProxy engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=0, pool_size=5) def task(arg): cur = engine.execute("select * from t1") result = cur.fetchall() cur.close() print(result) for i in range(20): t = threading.Thread(target=task, args=(i,)) t.start()
方式三：
import time import threading import sqlalchemy from sqlalchemy import create_engine from sqlalchemy.engine.base import Engine engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=0, pool_size=5) def task(arg): conn = engine.contextual_connect() with conn: cur = conn.execute( "select * from t1" ) result = cur.fetchall() print(result) for i in range(20): t = threading.Thread(target=task, args=(i,)) t.start()
方式一：
from sqlalchemy.orm import sessionmaker from sqlalchemy import create_engine from models import Student engine = create_engine( "mysql+pymysql://root:123456@127.0.0.1:3306/databasename?charset=utf8", max_overflow=0 # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30 # 池中没有线程最多等待的时间，否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收) SessionFactory = sessionmaker(bind=engine) def task(): # 去连接池获取一个连接 session = SessionFactory() ret = session.query(Student).all() session.close()
方式二：(推荐使用，基于Threading.Locak实现)
from sqlalchemy.orm import sessionmaker from sqlalchemy import create_engine from models import Student engine = create_engine( "mysql+pymysql://root:123456@127.0.0.1:3306/databasename?charset=utf8", max_overflow=0 # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30 # 池中没有线程最多等待的时间，否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收) SessionFactory = sessionmaker(bind=engine) session = scoped_session(SessionFactory) def task(): ret = session.query(Student).all() session.remove()
标签：err user span 展示 params model == ocs cts
原文地址：https://www.cnblogs.com/harryblog/p/11865891.html
