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Legal Studies查找 MongoDB 中数组元素具有特定值的文件？
为了匹配 MongoDB 中的文件，请使用 $elemMatch。我们首先创建一个包含文件的集合 −
> db.demo15.insertOne({"Details":[{"Score":56},{"Score":78}]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e0f7806d7df943a7cec4fab")
}
> db.demo15.insertOne({"Details":[{"Score":86},{"Score":86}]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e0f7817d7df943a7cec4fac")
}
> db.demo15.insertOne({"Details":[{"Score":97},{"Score":85}]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e0f7823d7df943a7cec4fad")
}以下是使用 find() 方法显示集合中所有文件时的查询 −
> db.demo15.find();
这将产生以下输出 −
{ "_id" : ObjectId("5e0f7806d7df943a7cec4fab"), "Details" : [ { "Score" : 56 }, { "Score" : 78 } ] }
{ "_id" : ObjectId("5e0f7817d7df943a7cec4fac"), "Details" : [ { "Score" : 86 }, { "Score" : 86 } ] }
{ "_id" : ObjectId("5e0f7823d7df943a7cec4fad"), "Details" : [ { "Score" : 97 }, { "Score" : 85 } ] }以下是查找数组中的所有元素都具有特定值的文件的查询 −
> db.demo15.find({
... "Details.Score" : {
... $exists : true
... },
... "Details" : {
... $not : {
... $elemMatch : {
... "Score" : {
... $ne : 86
... }
... }
... }
... }
... });这将产生以下输出 −
{ "_id" : ObjectId("5e0f7817d7df943a7cec4fac"), "Details" : [ { "Score" : 86 }, { "Score" : 86 } ] }
更新于： 01-Apr-2020
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