M101 Homework 2.2

最新推荐文章于 2025-04-22 14:46:34 发布

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本文介绍如何使用Python和pymongo库实现MongoDB中特定类型数据的批量删除操作，包括通过设置查询条件筛选数据并按指定字段排序，最后执行删除操作。

本人写的第一个python程序：

# M101 Week2 - CRUD Homework 2.2
import pymongo
import sys

# establish a connection to the database
connection = pymongo.Connection("mongodb://localhost", safe=True)
db = connection.students
grades = db.grades

def hw2_2():
    for i in range(0, 200):
        query = {'type':'homework', 'student_id': i}
        selector = {'student_id':1, '_id':1, 'score':1}
        
        try:
            cursor = grades.find( query, selector )
            cursor = cursor.sort([('student_id',pymongo.ASCENDING),('score',pymongo.ASCENDING)])
        
        except:
            print "Unexpected error:", sys.exc_info()[0]
            raise

        for hw in cursor:
            print "delete", hw
            grades.remove(hw)
            break

hw2_2()