python - Python 中的游标与连接

Question

在 Python 中哪个比其他的更高效。我的要求是在我们关闭应用程序之前建立一个连接。

我有两个类，一个是建立和获取连接/游标，使用它我可以在我的服务中获取和获取数据。在 python 中遵循 MVC :)

一个 DBConnection 类

import pyodbc

class Connection:
    def getconnection(self):
        conn =  pyodbc.connect('Driver={SQL Server};Server=.\SQLEXPRESS;Database=School;Trusted_Connection=yes;')
        print("Connection Established")
        #cursor = conn.cursor()
        return conn

    def getcursor(self):
        conn = pyodbc.connect('Driver={SQL Server};Server=.\SQLEXPRESS;Database=School;Trusted_Connection=yes;')
        print("Connection Established")
        cursor = conn.cursor()
        return cursor

和一个服务类

import Connection
import pyodbc

class StudentDataService:

    connection = Connection.Connection().getconnection()
    cursor = Connection.Connection().getcursor()

    def getstudentdata(self):
        print("In method getStudentdata()")
        try:
            row = self.connection.execute('select * from StudentGrade')
            studentList = list(row)
            return studentList
        except pyodbc.DatabaseError as err:
            print("Error Occurred while fetching Student Records", err)
            return None
        finally:
            self.connection.close()

    def getcursorstudentdata(self):
        print("In method getcursorstudentdata()")
        try:
            row = self.cursor.execute('select * from StudentGrade')
            studentList = list(row)
            return studentList
        except pyodbc.DatabaseError as err:
            print("Error Occurred while fetching Student Records", err)
            return None
        finally:
            self.cursor.close()


stu = StudentDataService()
print(stu.getstudentdata())
print("++++++++++++++++++++++++++++++++")
print(stu.getcursorstudentdata())

两者都给我结果

Connection Established
Connection Established
In method getStudentdata()
[(1, 2021, 2, Decimal('4.00')), (2, 2030, 2, Decimal('3.50')),... ]
++++++++++++++++++++++++++++++++
In method getcursorstudentdata()
[(1, 2021, 2, Decimal('4.00')), (2, 2030, 2, Decimal('3.50')),... ]

所以我的困惑是，使用哪个？

Answer 1

在pyodbc中，connection.execute只是为了方便创建游标和执行cursor.execute。这包含在文档中:

https://github.com/mkleehammer/pyodbc/wiki/Connection#execute

execute()

This function is not part of the Python DB API.

Creates a new Cursor object, calls its execute method, and returns the new cursor.

num_products = cnxn.execute("SELECT COUNT(*) FROM product")

See Cursor.execute() for more details. This is a convenience method that is not part of the DB API. Since a new Cursor is allocated by each call, this should not be used if more than one SQL statement needs to be executed on the connection.

如有疑问，只需使用Cursor.execute。