實用：python中sqlalchemy中mysql數據庫的簡單查詢和複雜查詢

import sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column,Integer,String,inspect,DATE,Enum,and_,or_,not_
from sqlalchemy.orm import sessionmaker

Base = declarative_base()

def show(emps):
    for x in emps:
        print(x)
    print('',end='\n\n')

class MyEnum(Enum):
    M = 'M'
    F = 'F'


class Employee(Base):
    __tablename__ = 'employees'
    emp_no = Column(Integer,primary_key=True)
    birth_date = Column(DATE,nullable=False)
    first_name = Column(String(14),nullable=False)
    last_name = Column(String(16),nullable=False)
    # gender = Column(MyEnum())
    hire_date = Column(DATE,nullable=False)

    def __repr__(self):
        return '<{} emp_no:{} name:{}>'.format(self.__class__.__name__,self.emp_no,'{}.{}'.format(self.first_name,self.last_name))

    __str__ = __repr__


host = '172.20.10.11'
port = '3306'
user = 'root'
passwd = '123456'
database = 'test'


conn_str = 'mysql+pymysql://{}:{}@{}:{}/{}'.format(user,passwd,host,port,database)
engine = sqlalchemy.create_engine(conn_str,echo=True)
Base.metadata.create_all(engine)
Session = sessionmaker()
session = Session(bind=engine)

#簡單條件查詢
print('#############################################################')
emps = session.query(Employee).filter(Employee.emp_no > 10015)
show(emps)

#複雜條件查詢
#1.AND
print('-------------------------------------------------------------')
emps = session.query(Employee).filter(Employee.emp_no > 10015).filter(Employee.emp_no < 10018)
show(emps)
print('-------------------------------------------------------------')
emps = session.query(Employee).filter(and_(Employee.emp_no > 10015,Employee.emp_no < 10018))
show(emps)
print('-------------------------------------------------------------')
emps = session.query(Employee).filter((Employee.emp_no > 10015) & (Employee.emp_no < 10018))
show(emps)

#2.OR
print('+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++')
emps = session.query(Employee).filter(or_(Employee.emp_no > 10018,Employee.emp_no < 10003))
show(emps)
print('+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++')
emps = session.query(Employee).filter((Employee.emp_no > 10018) | (Employee.emp_no < 10003))
show(emps)

#3.NOT
print('@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@')
emps = session.query(Employee).filter(not_(Employee.emp_no < 10018))
show(emps)
print('@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@')
emps = session.query(Employee).filter(~(Employee.emp_no < 10018))
show(emps)


#4.IN
print('^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^')
emplist = [10010,10015,10018]
emps = session.query(Employee).filter(Employee.emp_no.in_(emplist))
show(emps)

#5.NOT IN
print('^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^')
emplist = [10010,10015,10018]
emps = session.query(Employee).filter(~Employee.emp_no.in_(emplist))
show(emps)

#6.LIKE
print('!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!')
emps = session.query(Employee).filter(Employee.last_name.like('P%'))
show(emps)

#7.ASC（升序）
print('$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$')
emps = session.query(Employee).filter(Employee.emp_no > 10010).order_by(Employee.emp_no)
show(emps)
print('$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$')
emps = session.query(Employee).filter(Employee.emp_no > 10010).order_by(Employee.emp_no.asc())
show(emps)

#8.DESC（降序）
print('$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$')
emps = session.query(Employee).filter(Employee.emp_no > 10010).order_by(Employee.emp_no.desc())
show(emps)

#9.多列排序
print('$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$')
emps = session.query(Employee).filter(Employee.emp_no > 10010).order_by(Employee.last_name).order_by(Employee.emp_no.desc())
show(emps)

#10.分頁
print('***********************************************************')
emps = session.query(Employee).limit(4)
show(emps)
print('***********************************************************')
emps = session.query(Employee).limit(4).offset(18)
show(emps)

#11.消費者方法
#總行數（聚合函數）
print('???????????????????????????????????????????????????????????')
emps = session.query(Employee)
print(len(list(emps)))
print('???????????????????????????????????????????????????????????')
print(emps.count())
#取所有數據
print('???????????????????????????????????????????????????????????')
print(emps.all())
#取一行
# print(emps.one()) #返回一行，如果查詢結果爲多行則拋異常
print('???????????????????????????????????????????????????????????')
print(emps.limit(1).one())
#刪除delete by query
print('???????????????????????????????????????????????????????????')
session.query(Employee).filter(Employee.emp_no > 10018).delete()
# session.commit() #提交則刪除

運行結果：

2019-08-04 10:25:26,329 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'sql_mode'
2019-08-04 10:25:26,329 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 10:25:26,331 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'lower_case_table_names'
2019-08-04 10:25:26,331 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 10:25:26,334 INFO sqlalchemy.engine.base.Engine SELECT DATABASE()
2019-08-04 10:25:26,334 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 10:25:26,336 INFO sqlalchemy.engine.base.Engine show collation where `Charset` = 'utf8mb4' and `Collation` = 'utf8mb4_bin'
2019-08-04 10:25:26,337 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 10:25:26,339 INFO sqlalchemy.engine.base.Engine SELECT CAST('test plain returns' AS CHAR(60)) AS anon_1
2019-08-04 10:25:26,339 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 10:25:26,341 INFO sqlalchemy.engine.base.Engine SELECT CAST('test unicode returns' AS CHAR(60)) AS anon_1
2019-08-04 10:25:26,341 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 10:25:26,342 INFO sqlalchemy.engine.base.Engine SELECT CAST('test collated returns' AS CHAR CHARACTER SET utf8mb4) COLLATE utf8mb4_bin AS anon_1
2019-08-04 10:25:26,342 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 10:25:26,344 INFO sqlalchemy.engine.base.Engine DESCRIBE `employees`
2019-08-04 10:25:26,344 INFO sqlalchemy.engine.base.Engine {}
#############################################################
2019-08-04 10:25:26,350 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2019-08-04 10:25:26,351 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s
2019-08-04 10:25:26,351 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10015}
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10017 name:Cristinel.Bouloucos>
<Employee emp_no:10018 name:Kazuhide.Peha>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


-------------------------------------------------------------
2019-08-04 10:25:26,354 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s AND employees.emp_no < %(emp_no_2)s
2019-08-04 10:25:26,354 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10015, 'emp_no_2': 10018}
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10017 name:Cristinel.Bouloucos>


-------------------------------------------------------------
2019-08-04 10:25:26,357 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s AND employees.emp_no < %(emp_no_2)s
2019-08-04 10:25:26,357 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10015, 'emp_no_2': 10018}
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10017 name:Cristinel.Bouloucos>


-------------------------------------------------------------
2019-08-04 10:25:26,360 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s AND employees.emp_no < %(emp_no_2)s
2019-08-04 10:25:26,360 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10015, 'emp_no_2': 10018}
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10017 name:Cristinel.Bouloucos>


+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2019-08-04 10:25:26,363 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s OR employees.emp_no < %(emp_no_2)s
2019-08-04 10:25:26,363 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10018, 'emp_no_2': 10003}
<Employee emp_no:10001 name:Georgi.Facello>
<Employee emp_no:10002 name:Bezalel.Simmel>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2019-08-04 10:25:26,366 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s OR employees.emp_no < %(emp_no_2)s
2019-08-04 10:25:26,366 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10018, 'emp_no_2': 10003}
<Employee emp_no:10001 name:Georgi.Facello>
<Employee emp_no:10002 name:Bezalel.Simmel>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
2019-08-04 10:25:26,369 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no >= %(emp_no_1)s
2019-08-04 10:25:26,369 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10018}
<Employee emp_no:10018 name:Kazuhide.Peha>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
2019-08-04 10:25:26,372 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no >= %(emp_no_1)s
2019-08-04 10:25:26,372 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10018}
<Employee emp_no:10018 name:Kazuhide.Peha>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2019-08-04 10:25:26,375 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no IN (%(emp_no_1)s, %(emp_no_2)s, %(emp_no_3)s)
2019-08-04 10:25:26,375 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010, 'emp_no_3': 10018, 'emp_no_2': 10015}
<Employee emp_no:10010 name:Duangkaew.Piveteau>
<Employee emp_no:10015 name:Guoxiang.Nooteboom>
<Employee emp_no:10018 name:Kazuhide.Peha>


^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2019-08-04 10:25:26,378 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no NOT IN (%(emp_no_1)s, %(emp_no_2)s, %(emp_no_3)s)
2019-08-04 10:25:26,378 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010, 'emp_no_3': 10018, 'emp_no_2': 10015}
<Employee emp_no:10001 name:Georgi.Facello>
<Employee emp_no:10002 name:Bezalel.Simmel>
<Employee emp_no:10003 name:Parto.Bamford>
<Employee emp_no:10004 name:Chirstian.Koblick>
<Employee emp_no:10005 name:Kyoichi.Maliniak>
<Employee emp_no:10006 name:Anneke.Preusig>
<Employee emp_no:10007 name:Tzvetan.Zielinski>
<Employee emp_no:10008 name:Saniya.Kalloufi>
<Employee emp_no:10009 name:Sumant.Peac>
<Employee emp_no:10011 name:Mary.Sluis>
<Employee emp_no:10012 name:Patricio.Bridgland>
<Employee emp_no:10013 name:Eberhardt.Terkki>
<Employee emp_no:10014 name:Berni.Genin>
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10017 name:Cristinel.Bouloucos>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2019-08-04 10:25:26,382 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.last_name LIKE %(last_name_1)s
2019-08-04 10:25:26,382 INFO sqlalchemy.engine.base.Engine {'last_name_1': 'P%'}
<Employee emp_no:10006 name:Anneke.Preusig>
<Employee emp_no:10009 name:Sumant.Peac>
<Employee emp_no:10010 name:Duangkaew.Piveteau>
<Employee emp_no:10018 name:Kazuhide.Peha>


$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
2019-08-04 10:25:26,385 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s ORDER BY employees.emp_no
2019-08-04 10:25:26,385 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010}
<Employee emp_no:10011 name:Mary.Sluis>
<Employee emp_no:10012 name:Patricio.Bridgland>
<Employee emp_no:10013 name:Eberhardt.Terkki>
<Employee emp_no:10014 name:Berni.Genin>
<Employee emp_no:10015 name:Guoxiang.Nooteboom>
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10017 name:Cristinel.Bouloucos>
<Employee emp_no:10018 name:Kazuhide.Peha>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
2019-08-04 10:25:26,388 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s ORDER BY employees.emp_no ASC
2019-08-04 10:25:26,388 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010}
<Employee emp_no:10011 name:Mary.Sluis>
<Employee emp_no:10012 name:Patricio.Bridgland>
<Employee emp_no:10013 name:Eberhardt.Terkki>
<Employee emp_no:10014 name:Berni.Genin>
<Employee emp_no:10015 name:Guoxiang.Nooteboom>
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10017 name:Cristinel.Bouloucos>
<Employee emp_no:10018 name:Kazuhide.Peha>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
2019-08-04 10:25:26,391 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s ORDER BY employees.emp_no DESC
2019-08-04 10:25:26,392 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010}
<Employee emp_no:10020 name:Mayuko.Warwick>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10018 name:Kazuhide.Peha>
<Employee emp_no:10017 name:Cristinel.Bouloucos>
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10015 name:Guoxiang.Nooteboom>
<Employee emp_no:10014 name:Berni.Genin>
<Employee emp_no:10013 name:Eberhardt.Terkki>
<Employee emp_no:10012 name:Patricio.Bridgland>
<Employee emp_no:10011 name:Mary.Sluis>


$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
2019-08-04 10:25:26,395 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
WHERE employees.emp_no > %(emp_no_1)s ORDER BY employees.last_name, employees.emp_no DESC
2019-08-04 10:25:26,395 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010}
<Employee emp_no:10017 name:Cristinel.Bouloucos>
<Employee emp_no:10012 name:Patricio.Bridgland>
<Employee emp_no:10016 name:Kazuhito.Cappelletti>
<Employee emp_no:10014 name:Berni.Genin>
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10015 name:Guoxiang.Nooteboom>
<Employee emp_no:10018 name:Kazuhide.Peha>
<Employee emp_no:10011 name:Mary.Sluis>
<Employee emp_no:10013 name:Eberhardt.Terkki>
<Employee emp_no:10020 name:Mayuko.Warwick>


***********************************************************
2019-08-04 10:25:26,398 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
 LIMIT %(param_1)s
2019-08-04 10:25:26,399 INFO sqlalchemy.engine.base.Engine {'param_1': 4}
<Employee emp_no:10001 name:Georgi.Facello>
<Employee emp_no:10002 name:Bezalel.Simmel>
<Employee emp_no:10003 name:Parto.Bamford>
<Employee emp_no:10004 name:Chirstian.Koblick>


***********************************************************
2019-08-04 10:25:26,401 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
 LIMIT %(param_1)s, %(param_2)s
2019-08-04 10:25:26,401 INFO sqlalchemy.engine.base.Engine {'param_1': 18, 'param_2': 4}
<Employee emp_no:10019 name:Lillian.Haddadi>
<Employee emp_no:10020 name:Mayuko.Warwick>


???????????????????????????????????????????????????????????
2019-08-04 10:25:26,404 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees
2019-08-04 10:25:26,404 INFO sqlalchemy.engine.base.Engine {}
20
???????????????????????????????????????????????????????????
2019-08-04 10:25:26,409 INFO sqlalchemy.engine.base.Engine SELECT count(*) AS count_1 
FROM (SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees) AS anon_1
2019-08-04 10:25:26,409 INFO sqlalchemy.engine.base.Engine {}
20
???????????????????????????????????????????????????????????
2019-08-04 10:25:26,411 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees
2019-08-04 10:25:26,411 INFO sqlalchemy.engine.base.Engine {}
[<Employee emp_no:10001 name:Georgi.Facello>, <Employee emp_no:10002 name:Bezalel.Simmel>, <Employee emp_no:10003 name:Parto.Bamford>, <Employee emp_no:10004 name:Chirstian.Koblick>, <Employee emp_no:10005 name:Kyoichi.Maliniak>, <Employee emp_no:10006 name:Anneke.Preusig>, <Employee emp_no:10007 name:Tzvetan.Zielinski>, <Employee emp_no:10008 name:Saniya.Kalloufi>, <Employee emp_no:10009 name:Sumant.Peac>, <Employee emp_no:10010 name:Duangkaew.Piveteau>, <Employee emp_no:10011 name:Mary.Sluis>, <Employee emp_no:10012 name:Patricio.Bridgland>, <Employee emp_no:10013 name:Eberhardt.Terkki>, <Employee emp_no:10014 name:Berni.Genin>, <Employee emp_no:10015 name:Guoxiang.Nooteboom>, <Employee emp_no:10016 name:Kazuhito.Cappelletti>, <Employee emp_no:10017 name:Cristinel.Bouloucos>, <Employee emp_no:10018 name:Kazuhide.Peha>, <Employee emp_no:10019 name:Lillian.Haddadi>, <Employee emp_no:10020 name:Mayuko.Warwick>]
???????????????????????????????????????????????????????????
2019-08-04 10:25:26,415 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.hire_date AS employees_hire_date 
FROM employees 
 LIMIT %(param_1)s
2019-08-04 10:25:26,415 INFO sqlalchemy.engine.base.Engine {'param_1': 1}
<Employee emp_no:10001 name:Georgi.Facello>
???????????????????????????????????????????????????????????
2019-08-04 10:25:26,417 INFO sqlalchemy.engine.base.Engine DELETE FROM employees WHERE employees.emp_no > %(emp_no_1)s
2019-08-04 10:25:26,417 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10018}

改進：（聚合函數與分組）

import sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column,Integer,String,inspect,DATE,Enum,and_,or_,not_
from sqlalchemy.orm import sessionmaker
from sqlalchemy import func

Base = declarative_base()

def show(emps):
    for x in emps:
        print(x)
    print('',end='\n\n')


class Employee(Base):
    __tablename__ = 'employees'
    emp_no = Column(Integer,primary_key=True)
    birth_date = Column(DATE,nullable=False)
    first_name = Column(String(14),nullable=False)
    last_name = Column(String(16),nullable=False)
    # gender = Column(MyEnum(Enum,M='M'),nullable=False)
    hire_date = Column(DATE,nullable=False)

    def __repr__(self):
        return '<{} emp_no:{} name:{}>'.format(self.__class__.__name__,self.emp_no,'{}.{}'.format(self.first_name,self.last_name))

    __str__ = __repr__


host = '172.20.10.11'
port = '3306'
user = 'root'
passwd = '123456'
database = 'test'


conn_str = 'mysql+pymysql://{}:{}@{}:{}/{}'.format(user,passwd,host,port,database)
engine = sqlalchemy.create_engine(conn_str,echo=True)
Base.metadata.create_all(engine)
Session = sessionmaker()
session = Session(bind=engine)

print('------------------------------------------------')
query = session.query(func.count(Employee.emp_no))
print(query.one())
print(query.scalar())

#max/min/avg
print('------------------------------------------------')
print(session.query(func.max(Employee.emp_no)).scalar())
print('------------------------------------------------')
print(session.query(func.min(Employee.emp_no)).scalar())
print('------------------------------------------------')
print(session.query(func.avg(Employee.emp_no)).scalar())

#分組
print(session.query(func.count(Employee.emp_no)).group_by(Employee.emp_no).all())

運行結果：

2019-08-04 11:00:05,530 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'sql_mode'
2019-08-04 11:00:05,531 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 11:00:05,532 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'lower_case_table_names'
2019-08-04 11:00:05,532 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 11:00:05,534 INFO sqlalchemy.engine.base.Engine SELECT DATABASE()
2019-08-04 11:00:05,535 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 11:00:05,536 INFO sqlalchemy.engine.base.Engine show collation where `Charset` = 'utf8mb4' and `Collation` = 'utf8mb4_bin'
2019-08-04 11:00:05,536 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 11:00:05,539 INFO sqlalchemy.engine.base.Engine SELECT CAST('test plain returns' AS CHAR(60)) AS anon_1
2019-08-04 11:00:05,539 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 11:00:05,541 INFO sqlalchemy.engine.base.Engine SELECT CAST('test unicode returns' AS CHAR(60)) AS anon_1
2019-08-04 11:00:05,541 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 11:00:05,542 INFO sqlalchemy.engine.base.Engine SELECT CAST('test collated returns' AS CHAR CHARACTER SET utf8mb4) COLLATE utf8mb4_bin AS anon_1
2019-08-04 11:00:05,542 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 11:00:05,545 INFO sqlalchemy.engine.base.Engine DESCRIBE `employees`
2019-08-04 11:00:05,545 INFO sqlalchemy.engine.base.Engine {}
------------------------------------------------
2019-08-04 11:00:05,553 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2019-08-04 11:00:05,553 INFO sqlalchemy.engine.base.Engine SELECT count(employees.emp_no) AS count_1 
FROM employees
2019-08-04 11:00:05,554 INFO sqlalchemy.engine.base.Engine {}
(20,)
2019-08-04 11:00:05,556 INFO sqlalchemy.engine.base.Engine SELECT count(employees.emp_no) AS count_1 
FROM employees
2019-08-04 11:00:05,556 INFO sqlalchemy.engine.base.Engine {}
20
------------------------------------------------
2019-08-04 11:00:05,559 INFO sqlalchemy.engine.base.Engine SELECT max(employees.emp_no) AS max_1 
FROM employees
2019-08-04 11:00:05,559 INFO sqlalchemy.engine.base.Engine {}
10020
------------------------------------------------
2019-08-04 11:00:05,561 INFO sqlalchemy.engine.base.Engine SELECT min(employees.emp_no) AS min_1 
FROM employees
2019-08-04 11:00:05,561 INFO sqlalchemy.engine.base.Engine {}
10001
------------------------------------------------
2019-08-04 11:00:05,563 INFO sqlalchemy.engine.base.Engine SELECT avg(employees.emp_no) AS avg_1 
FROM employees
2019-08-04 11:00:05,564 INFO sqlalchemy.engine.base.Engine {}
10010.5000
2019-08-04 11:00:05,566 INFO sqlalchemy.engine.base.Engine SELECT count(employees.emp_no) AS count_1 
FROM employees GROUP BY employees.emp_no
2019-08-04 11:00:05,566 INFO sqlalchemy.engine.base.Engine {}
[(1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,), (1,)]

改進：（關聯查詢）

import sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column,Integer,String,inspect,DATE,Enum,and_,or_,not_,ForeignKey
from sqlalchemy.orm import sessionmaker,relationships
from sqlalchemy import func
import enum

Base = declarative_base()

def show(emps):
    for x in emps:
        print(x)
    print('',end='\n\n')

class MyEnum(enum.Enum):
    M = 'M'
    F = 'F'

class Employee(Base):
    __tablename__ = 'employees'
    emp_no = Column(Integer,primary_key=True)
    birth_date = Column(DATE,nullable=False)
    first_name = Column(String(14),nullable=False)
    last_name = Column(String(16),nullable=False)
    gender = Column(Enum(MyEnum),nullable=False)
    hire_date = Column(DATE,nullable=False)

    # depts = relationships('Dept_emp') #關聯要使用“類名引號+外鍵”此處不寫外鍵是由於表定義中已經設置了外鍵的定義

    def __repr__(self):
        return '<{} emp_no:{} name:{} gender={}>'.format(self.__class__.__name__,self.emp_no,'{}.{}'.format(self.first_name,self.last_name),self.gender.value)

    __str__ = __repr__


class Department(Base):
    __tablename__ = 'departments'

    dept_no = Column(String(4),primary_key=True)
    dept_name = Column(String(40),nullable=False,unique=True)

    def __repr__(self):
        return '{} no={} name={}'.format(type(self).__name,self.dept_no,self.dept_name)

class Dept_emp(Base):
    __tablename__ = 'dept_emp'

    emp_no = Column(Integer,ForeignKey('emplopyees.emp_no'),primary_key=True) #外鍵中要使用“表名+字段”
    dept_no = Column(String(4),ForeignKey('departments.dept_no',ondelete='CASCADE'),primary_key=True)
    from_date = Column(DATE,nullable=False)
    to_date = Column(DATE,nullable=False)

    def __repr__(self):
        return '{} no={} name={}'.format(type(self).__name__,self.emp_no,self.dept_no)


host = '172.20.10.11'
port = '3306'
user = 'root'
passwd = '123456'
database = 'test'


conn_str = 'mysql+pymysql://{}:{}@{}:{}/{}'.format(user,passwd,host,port,database)
engine = sqlalchemy.create_engine(conn_str,echo=True)
Base.metadata.create_all(engine)
Session = sessionmaker()
session = Session(bind=engine)

#查詢員工所在部門編號
#隱匿內連接
print('----------------------------------------------------------------------')
results = session.query(Employee,Dept_emp).filter(Employee.emp_no == Dept_emp.emp_no).filter(Employee.emp_no == 10010).all()#查詢使用“類名+屬性”
print(results)

#JOIN
print('----------------------------------------------------------------------')
results = session.query(Employee,Dept_emp).join(Dept_emp,Employee.emp_no == Dept_emp.emp_no).filter(Employee.emp_no == 10010).all()
print(results)
results = session.query(func.count(Employee.emp_no)).join(Dept_emp,Employee.emp_no == Dept_emp.emp_no).filter(Employee.emp_no == 10010).all()
print(results)#上面的結果只顯示一個值（因爲以employee表各字段的值來顯示自動去重了，但從統計結果看有2個值）

解決兩條結果一樣被自動去重的問題（關聯查詢顯示所有結果）

import sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column,Integer,String,inspect,Date,Enum,and_,or_,not_,ForeignKey
from sqlalchemy.orm import sessionmaker,relationship
from sqlalchemy import func
import enum

Base = declarative_base()

def show(emps):
    for x in emps:
        print(x)
    print('',end='\n\n')

class MyEnum(enum.Enum):
    M = 'M'
    F = 'F'

class Employee(Base):
    __tablename__ = 'employees'
    emp_no = Column(Integer,primary_key=True)
    birth_date = Column(Date,nullable=False)
    first_name = Column(String(14),nullable=False)
    last_name = Column(String(16),nullable=False)
    gender = Column(Enum(MyEnum),nullable=False)
    hire_date = Column(Date,nullable=False)
    dept_emps = relationship('Dept_emp') #關聯要使用“類名引號+外鍵”此處不寫外鍵是由於表定義中已經設置了外鍵的定義

    def __repr__(self):
        return '<{} emp_no:{} name:{} gender={}> relation={}'.format(self.__class__.__name__,self.emp_no,'{}.{}'.format(self.first_name,self.last_name),self.gender.value,self.dept_emps)

    __str__ = __repr__


class Department(Base):
    __tablename__ = 'departments'

    dept_no = Column(String(4),primary_key=True)
    dept_name = Column(String(40),nullable=False,unique=True)

    def __repr__(self):
        return '{} no={} name={}'.format(type(self).__name,self.dept_no,self.dept_name)

class Dept_emp(Base):
    __tablename__ = 'dept_emp'

    emp_no = Column(Integer, ForeignKey('employees.emp_no',ondelete='CASCADE'),primary_key=True) #外鍵中要使用“表名+字段”
    dept_no = Column(String(4),ForeignKey('departments.dept_no',ondelete='CASCADE'),primary_key=True)
    from_date = Column(Date,nullable=False)
    to_date = Column(Date,nullable=False)


    def __repr__(self):
        return '{} no={} name={}'.format(type(self).__name__,self.emp_no,self.dept_no)

host = '172.20.10.11'
port = '3306'
user = 'root'
passwd = '123456'
database = 'test'


conn_str = 'mysql+pymysql://{}:{}@{}:{}/{}'.format(user,passwd,host,port,database)
engine = sqlalchemy.create_engine(conn_str,echo=True)
Base.metadata.create_all(engine)
Session = sessionmaker()
session = Session(bind=engine)

#查詢員工所在部門編號
#第一種
print('----------------------------------------------------------------------')
results = session.query(Employee).join(Dept_emp).filter(Employee.emp_no == Dept_emp.emp_no).filter(Employee.emp_no == 10010).all()
print(results)

#第二種
print('----------------------------------------------------------------------')
results = session.query(Employee).join(Dept_emp,Employee.emp_no == Dept_emp.emp_no).filter(Employee.emp_no == 10010).all()
print(results)

#第三種
print('----------------------------------------------------------------------')
results = session.query(Employee).join(Dept_emp,(Employee.emp_no == Dept_emp.emp_no) & (Employee.emp_no == 10010)).all()
print(results)

運行結果：

2019-08-04 15:58:59,923 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'sql_mode'
2019-08-04 15:58:59,924 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,925 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'lower_case_table_names'
2019-08-04 15:58:59,926 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,928 INFO sqlalchemy.engine.base.Engine SELECT DATABASE()
2019-08-04 15:58:59,928 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,929 INFO sqlalchemy.engine.base.Engine show collation where `Charset` = 'utf8mb4' and `Collation` = 'utf8mb4_bin'
2019-08-04 15:58:59,929 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,931 INFO sqlalchemy.engine.base.Engine SELECT CAST('test plain returns' AS CHAR(60)) AS anon_1
2019-08-04 15:58:59,931 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,933 INFO sqlalchemy.engine.base.Engine SELECT CAST('test unicode returns' AS CHAR(60)) AS anon_1
2019-08-04 15:58:59,933 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,934 INFO sqlalchemy.engine.base.Engine SELECT CAST('test collated returns' AS CHAR CHARACTER SET utf8mb4) COLLATE utf8mb4_bin AS anon_1
2019-08-04 15:58:59,934 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,936 INFO sqlalchemy.engine.base.Engine DESCRIBE `employees`
2019-08-04 15:58:59,936 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,938 INFO sqlalchemy.engine.base.Engine DESCRIBE `departments`
2019-08-04 15:58:59,938 INFO sqlalchemy.engine.base.Engine {}
2019-08-04 15:58:59,940 INFO sqlalchemy.engine.base.Engine DESCRIBE `dept_emp`
2019-08-04 15:58:59,940 INFO sqlalchemy.engine.base.Engine {}
----------------------------------------------------------------------
2019-08-04 15:58:59,947 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2019-08-04 15:58:59,949 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.gender AS employees_gender, employees.hire_date AS employees_hire_date 
FROM employees INNER JOIN dept_emp ON employees.emp_no = dept_emp.emp_no 
WHERE employees.emp_no = dept_emp.emp_no AND employees.emp_no = %(emp_no_1)s
2019-08-04 15:58:59,949 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010}
2019-08-04 15:58:59,952 INFO sqlalchemy.engine.base.Engine SELECT dept_emp.emp_no AS dept_emp_emp_no, dept_emp.dept_no AS dept_emp_dept_no, dept_emp.from_date AS dept_emp_from_date, dept_emp.to_date AS dept_emp_to_date 
FROM dept_emp 
WHERE %(param_1)s = dept_emp.emp_no
2019-08-04 15:58:59,952 INFO sqlalchemy.engine.base.Engine {'param_1': 10010}
[<Employee emp_no:10010 name:Duangkaew.Piveteau gender=F> relation=[Dept_emp no=10010 name=d004, Dept_emp no=10010 name=d006]]
----------------------------------------------------------------------
2019-08-04 15:58:59,955 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.gender AS employees_gender, employees.hire_date AS employees_hire_date 
FROM employees INNER JOIN dept_emp ON employees.emp_no = dept_emp.emp_no 
WHERE employees.emp_no = %(emp_no_1)s
2019-08-04 15:58:59,955 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010}
[<Employee emp_no:10010 name:Duangkaew.Piveteau gender=F> relation=[Dept_emp no=10010 name=d004, Dept_emp no=10010 name=d006]]
----------------------------------------------------------------------
2019-08-04 15:58:59,958 INFO sqlalchemy.engine.base.Engine SELECT employees.emp_no AS employees_emp_no, employees.birth_date AS employees_birth_date, employees.first_name AS employees_first_name, employees.last_name AS employees_last_name, employees.gender AS employees_gender, employees.hire_date AS employees_hire_date 
FROM employees INNER JOIN dept_emp ON employees.emp_no = dept_emp.emp_no AND employees.emp_no = %(emp_no_1)s
2019-08-04 15:58:59,958 INFO sqlalchemy.engine.base.Engine {'emp_no_1': 10010}
[<Employee emp_no:10010 name:Duangkaew.Piveteau gender=F> relation=[Dept_emp no=10010 name=d004, Dept_emp no=10010 name=d006]]