Mongodb 为什么可以'；它不显示有两位以上作者的书吗？
我应该找到ISBN，书名，以及出版商，这些书至少有两位作者，至少有三位作者 我所做的：Mongodb 为什么可以'；它不显示有两位以上作者的书吗？,mongodb,mongodb-query,aggregation-framework,Mongodb,Mongodb Query,Aggregation Framework,我应该找到ISBN，书名，以及出版商，这些书至少有两位作者，至少有三位作者 我所做的： db.Subject.aggregate([ {"$match": {$and: [{"subject.book.author.3": {$exists: false}}, {"subject.book.author.1": {$exists: true}}]}}, {&q
db.Subject.aggregate([
{"$match": {$and: [{"subject.book.author.3": {$exists: false}},
{"subject.book.author.1": {$exists: true}}]}},
{"$project": {"subject.book.ISBN": 1,"subject.book.bookTitle": 1,"subject.book.publisher": 1}}
]).pretty();
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"subTitle":"Algorithm and Problem Solving",
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"description":"Assignment 1 - Sorting and Seaarching, Linked Lists, and Stack and Queues" },
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"bookType":"textbook",
"bookTitle":"Introduction to the Design and Analysis of Algorithms",
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"publisher":"Pearson",
"author": [ "Anany Levitin" ] },
{ "ISBN":"13:978-0-13-231681-1",
"bookType":"reference",
"edition":3,
"yearPub":2005,
"publisher":"Pearson",
"author": [ "B A Forouzan", "D S Malik", "M K Sen Thomson" ] }
]
}
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db.Subject.insert(
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"subject": {
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"subTitle":"Procedural Programming",
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"description":"Assignment 1 - Basic Concepts: Sequential Designs" },
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"bookTitle":"C++ Programming - Program design including data structure",
"edition":6,
"yearPub":2013,
"publisher":"CENGAGE Learning",
"author": [ "Malik D S" ] },
{ "ISBN":"13:978-0-273-75983-6",
"bookType":"reference",
"bookTitle":"Starting Out With C++: From Control Structures through Objects",
"edition":7,
"yearPub":2012,
"publisher":"Addison-Wesley",
"author": [ "Tony Gaddis" ] },
]
}
}
)
db.Subject.insert(
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"subCode":"CSCI124",
"subTitle":"Applied Programming",
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"assessType":"Assignment",
"description":"Assignment 1 - Application on binary file processing" },
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"description":"Assignment 2 - Application on pointers" },
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"bookTitle":"Data Structures Using C++",
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"yearPub":2010,
"publisher":"CENGAGE Learning",
"author": [ "Malik D S" ] },
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"bookType":"reference",
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"yearPub":2013,
"publisher":"CENGAGE Learning",
"author": [ "Malik D S" ] },
{ "ISBN":"13:978-0-273-75983-6",
"bookType":"reference",
"bookTitle":"Starting Out With C++: From Control Structures through Objects",
"edition":7,
"yearPub":2012,
"publisher":"Addison-Wesley",
"author": [ "Tony Gaddis" ] }
]
}
}
)
db.Subject.insert(
{
"_id":ObjectId(),
"subject":{
"subCode":"CSCI235",
"subTitle":"Database Systems",
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"publisher":"Addison-Wesley",
"author": [ "Ramez Elmasri", "Shamkant B Navathe" ] },
{ "ISBN":"0-07-246563-8",
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"publisher":"McGraw-Hill",
"author": [ "Raghur Ramakrishnan", "Johannes Gehrke" ] } ]
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db.Subject.insert(
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"subject":{
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"subTitle":"Algorithm and Data Structures",
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"prerequisite": ["csci103"],
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"publisher":"The MIT Press",
"author": [ "Thomas H Cormen", "Charles E Leiserson", "Ronald L Riverst", "Clifford Stein" ] } ]
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db.Subject.insert(
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"subTitle":"Professional Practice and Ethics",
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{ "assessNum": 3,
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db.Subject.insert(
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"subTitle":"Final Year Project",
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db.collection.aggregate([
{
"$unwind": "$subject.book"
},
{
"$match": {
"subject.book.author.1": {
$exists: true
},
"subject.book.author.3": {
$exists: false
},
}
},
{
"$project": {
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])
您好，这不会返回任何内容检查此在我粘贴所有数据库脚本后，它显示无效配置：必须是像“[{u-id:1}，{u-id:2}]”这样的文档数组，或者必须匹配“db={collection:[{u-id:1}，{u-id:2}]”我已经更新了帖子并在中添加了完整的数据库。我不知道第一份文件出了什么问题，有两本书。一个有1个作者，另一个有3个作者。是否要在不输出第一本书的情况下输出此文档，或仅关闭此文档？
db.collection.aggregate([
{
"$unwind": "$subject.book"
},
{
"$match": {
"subject.book.author.1": {
$exists: true
},
"subject.book.author.3": {
$exists: false
},
}
},
{
"$project": {
"subject.book.ISBN": 1,
"subject.book.bookTitle": 1,
"subject.book.publisher": 1
}
}
])