python操作SQL
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python操作SQL
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pymysql
pymsql是Python中操作MySQL的模塊，其使用方法和MySQLdb幾乎相同
一、下載安裝
pip3 install pymysql二、操作使用
1、執(zhí)行SQL
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 import pymysql 4 5 # 創(chuàng)建連接 6 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1') 7 # 創(chuàng)建游標(biāo) 8 cursor = conn.cursor() 9 10 # 執(zhí)行SQL，并返回收影響行數(shù) 11 effect_row = cursor.execute("update hosts set host = '1.1.1.2'") 12 13 # 執(zhí)行SQL，并返回受影響行數(shù) 14 #effect_row = cursor.execute("update hosts set host = '1.1.1.2' where nid > %s", (1,)) 15 16 # 執(zhí)行SQL，并返回受影響行數(shù) 17 #effect_row = cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)]) 18 19 20 # 提交，不然無法保存新建或者修改的數(shù)據(jù) 21 conn.commit() 22 23 # 關(guān)閉游標(biāo) 24 cursor.close() 25 # 關(guān)閉連接 26 conn.close() View Code2、獲取新創(chuàng)建數(shù)據(jù)自增ID
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 import pymysql 4 5 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1') 6 cursor = conn.cursor() 7 cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)]) 8 conn.commit() 9 cursor.close() 10 conn.close() 11 12 # 獲取最新自增ID 13 new_id = cursor.lastrowid View Code3、獲取查詢數(shù)據(jù)
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 import pymysql 4 5 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1') 6 cursor = conn.cursor() 7 cursor.execute("select * from hosts") 8 9 # 獲取第一行數(shù)據(jù) 10 row_1 = cursor.fetchone() 11 12 # 獲取前n行數(shù)據(jù) 13 # row_2 = cursor.fetchmany(3) 14 # 獲取所有數(shù)據(jù) 15 # row_3 = cursor.fetchall() 16 17 conn.commit() 18 cursor.close() 19 conn.close() View Code注：在fetch數(shù)據(jù)時(shí)按照順序進(jìn)行，可以使用cursor.scroll(num,mode)來移動(dòng)游標(biāo)位置，如：
- cursor.scroll(1,mode='relative') ?# 相對(duì)當(dāng)前位置移動(dòng)
- cursor.scroll(2,mode='absolute') # 相對(duì)絕對(duì)位置移動(dòng)
4、fetch數(shù)據(jù)類型關(guān)于默認(rèn)獲取的數(shù)據(jù)是元祖類型，如果想要或者字典類型的數(shù)據(jù)，即：
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 import pymysql 4 5 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1') 6 7 # 游標(biāo)設(shè)置為字典類型 8 cursor = conn.cursor(cursor=pymysql.cursors.DictCursor) 9 r = cursor.execute("call p1()") 10 11 result = cursor.fetchone() 12 13 conn.commit() 14 cursor.close() 15 conn.close() View CodeSQLAlchemy
SQLAlchemy是Python編程語(yǔ)言下的一款ORM框架，該框架建立在數(shù)據(jù)庫(kù)API之上，使用關(guān)系對(duì)象映射進(jìn)行數(shù)據(jù)庫(kù)操作，簡(jiǎn)言之便是：將對(duì)象轉(zhuǎn)換成SQL，然后使用數(shù)據(jù)API執(zhí)行SQL并獲取執(zhí)行結(jié)果。
安裝：
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pip3 install SQLAlchemy?
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SQLAlchemy本身無法操作數(shù)據(jù)庫(kù)，其必須以來pymsql等第三方插件，Dialect用于和數(shù)據(jù)API進(jìn)行交流，根據(jù)配置文件的不同調(diào)用不同的數(shù)據(jù)庫(kù)API，從而實(shí)現(xiàn)對(duì)數(shù)據(jù)庫(kù)的操作，如：
MySQL-Pythonmysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>pymysqlmysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]MySQL-Connectormysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>cx_Oracleoracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]更多詳見：http://docs.sqlalchemy.org/en/latest/dialects/index.html一、內(nèi)部處理
使用 Engine/ConnectionPooling/Dialect 進(jìn)行數(shù)據(jù)庫(kù)操作，Engine使用ConnectionPooling連接數(shù)據(jù)庫(kù)，然后再通過Dialect執(zhí)行SQL語(yǔ)句。
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy import create_engineengine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)# 執(zhí)行SQL # cur = engine.execute( # "INSERT INTO hosts (host, color_id) VALUES ('1.1.1.22', 3)" # )# 新插入行自增ID # cur.lastrowid# 執(zhí)行SQL # cur = engine.execute( # "INSERT INTO hosts (host, color_id) VALUES(%s, %s)",[('1.1.1.22', 3),('1.1.1.221', 3),] # )# 執(zhí)行SQL # cur = engine.execute( # "INSERT INTO hosts (host, color_id) VALUES (%(host)s, %(color_id)s)", # host='1.1.1.99', color_id=3 # )# 執(zhí)行SQL # cur = engine.execute('select * from hosts') # 獲取第一行數(shù)據(jù) # cur.fetchone() # 獲取第n行數(shù)據(jù) # cur.fetchmany(3) # 獲取所有數(shù)據(jù) # cur.fetchall()二、ORM功能使用
使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 所有組件對(duì)數(shù)據(jù)進(jìn)行操作。根據(jù)類創(chuàng)建對(duì)象，對(duì)象轉(zhuǎn)換成SQL，執(zhí)行SQL。
1、創(chuàng)建表
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 from sqlalchemy.ext.declarative import declarative_base 4 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index 5 from sqlalchemy.orm import sessionmaker, relationship 6 from sqlalchemy import create_engine 7 8 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) 9 10 Base = declarative_base() 11 12 # 創(chuàng)建單表 13 class Users(Base): 14 __tablename__ = 'users' 15 id = Column(Integer, primary_key=True) 16 name = Column(String(32)) 17 extra = Column(String(16)) 18 19 __table_args__ = ( 20 UniqueConstraint('id', 'name', name='uix_id_name'), 21 Index('ix_id_name', 'name', 'extra'), 22 ) 23 24 25 # 一對(duì)多 26 class Favor(Base): 27 __tablename__ = 'favor' 28 nid = Column(Integer, primary_key=True) 29 caption = Column(String(50), default='red', unique=True) 30 31 32 class Person(Base): 33 __tablename__ = 'person' 34 nid = Column(Integer, primary_key=True) 35 name = Column(String(32), index=True, nullable=True) 36 favor_id = Column(Integer, ForeignKey("favor.nid")) 37 38 39 # 多對(duì)多 40 class Group(Base): 41 __tablename__ = 'group' 42 id = Column(Integer, primary_key=True) 43 name = Column(String(64), unique=True, nullable=False) 44 port = Column(Integer, default=22) 45 46 47 class Server(Base): 48 __tablename__ = 'server' 49 50 id = Column(Integer, primary_key=True, autoincrement=True) 51 hostname = Column(String(64), unique=True, nullable=False) 52 53 54 class ServerToGroup(Base): 55 __tablename__ = 'servertogroup' 56 nid = Column(Integer, primary_key=True, autoincrement=True) 57 server_id = Column(Integer, ForeignKey('server.id')) 58 group_id = Column(Integer, ForeignKey('group.id')) 59 60 61 def init_db(): 62 Base.metadata.create_all(engine) 63 64 65 def drop_db(): 66 Base.metadata.drop_all(engine) 67 注：設(shè)置外檢的另一種方式 ForeignKeyConstraint(['other_id'], ['othertable.other_id']) View Code2、操作表
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 from sqlalchemy.ext.declarative import declarative_base 4 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index 5 from sqlalchemy.orm import sessionmaker, relationship 6 from sqlalchemy import create_engine 7 8 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) 9 10 Base = declarative_base() 11 12 # 創(chuàng)建單表 13 class Users(Base): 14 __tablename__ = 'users' 15 id = Column(Integer, primary_key=True) 16 name = Column(String(32)) 17 extra = Column(String(16)) 18 19 __table_args__ = ( 20 UniqueConstraint('id', 'name', name='uix_id_name'), 21 Index('ix_id_name', 'name', 'extra'), 22 ) 23 24 def __repr__(self): 25 return "%s-%s" %(self.id, self.name) 26 27 # 一對(duì)多 28 class Favor(Base): 29 __tablename__ = 'favor' 30 nid = Column(Integer, primary_key=True) 31 caption = Column(String(50), default='red', unique=True) 32 33 def __repr__(self): 34 return "%s-%s" %(self.nid, self.caption) 35 36 class Person(Base): 37 __tablename__ = 'person' 38 nid = Column(Integer, primary_key=True) 39 name = Column(String(32), index=True, nullable=True) 40 favor_id = Column(Integer, ForeignKey("favor.nid")) 41 # 與生成表結(jié)構(gòu)無關(guān)，僅用于查詢方便 42 favor = relationship("Favor", backref='pers') 43 44 # 多對(duì)多 45 class ServerToGroup(Base): 46 __tablename__ = 'servertogroup' 47 nid = Column(Integer, primary_key=True, autoincrement=True) 48 server_id = Column(Integer, ForeignKey('server.id')) 49 group_id = Column(Integer, ForeignKey('group.id')) 50 group = relationship("Group", backref='s2g') 51 server = relationship("Server", backref='s2g') 52 53 class Group(Base): 54 __tablename__ = 'group' 55 id = Column(Integer, primary_key=True) 56 name = Column(String(64), unique=True, nullable=False) 57 port = Column(Integer, default=22) 58 # group = relationship('Group',secondary=ServerToGroup,backref='host_list') 59 60 61 class Server(Base): 62 __tablename__ = 'server' 63 64 id = Column(Integer, primary_key=True, autoincrement=True) 65 hostname = Column(String(64), unique=True, nullable=False) 66 67 68 69 70 def init_db(): 71 Base.metadata.create_all(engine) 72 73 74 def drop_db(): 75 Base.metadata.drop_all(engine) 76 77 78 Session = sessionmaker(bind=engine) 79 session = Session() 表結(jié)構(gòu)加數(shù)據(jù)庫(kù)連接 1 obj = Users(name="alex0", extra='sb') 2 session.add(obj) 3 session.add_all([ 4 Users(name="alex1", extra='sb'), 5 Users(name="alex2", extra='sb'), 6 ]) 7 session.commit() 增 1 session.query(Users).filter(Users.id > 2).delete() 2 session.commit() 刪 1 session.query(Users).filter(Users.id > 2).update({"name" : "099"}) 2 session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False) 3 session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate") 4 session.commit() 改 1 ret = session.query(Users).all() 2 ret = session.query(Users.name, Users.extra).all() 3 ret = session.query(Users).filter_by(name='alex').all() 4 ret = session.query(Users).filter_by(name='alex').first() 查 1 # 條件 2 ret = session.query(Users).filter_by(name='alex').all() 3 ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all() 4 ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all() 5 ret = session.query(Users).filter(Users.id.in_([1,3,4])).all() 6 ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all() 7 ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all() 8 from sqlalchemy import and_, or_ 9 ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all() 10 ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all() 11 ret = session.query(Users).filter( 12 or_( 13 Users.id < 2, 14 and_(Users.name == 'eric', Users.id > 3), 15 Users.extra != "" 16 )).all() 17 18 19 # 通配符 20 ret = session.query(Users).filter(Users.name.like('e%')).all() 21 ret = session.query(Users).filter(~Users.name.like('e%')).all() 22 23 # 限制 24 ret = session.query(Users)[1:2] 25 26 # 排序 27 ret = session.query(Users).order_by(Users.name.desc()).all() 28 ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all() 29 30 # 分組 31 from sqlalchemy.sql import func 32 33 ret = session.query(Users).group_by(Users.extra).all() 34 ret = session.query( 35 func.max(Users.id), 36 func.sum(Users.id), 37 func.min(Users.id)).group_by(Users.name).all() 38 39 ret = session.query( 40 func.max(Users.id), 41 func.sum(Users.id), 42 func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all() 43 44 # 連表 45 46 ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all() 47 48 ret = session.query(Person).join(Favor).all() 49 50 ret = session.query(Person).join(Favor, isouter=True).all() 51 52 53 # 組合 54 q1 = session.query(Users.name).filter(Users.id > 2) 55 q2 = session.query(Favor.caption).filter(Favor.nid < 2) 56 ret = q1.union(q2).all() 57 58 q1 = session.query(Users.name).filter(Users.id > 2) 59 q2 = session.query(Favor.caption).filter(Favor.nid < 2) 60 ret = q1.union_all(q2).all() 其他?
轉(zhuǎn)載于:https://www.cnblogs.com/kading/p/6090762.html
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