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我有一個集合中蒙戈在子文檔中多個領域蒙戈查詢
{
"_id": 1,
"favorites": {
"artist": "Picasso",
"food": "pizza"
},
"finished": [
17,
3
],
"badges": [
"blue",
"black"
],
"points": [
{
"points": 85,
"bo nus": 20
},
{
"points": 85,
"bonus": 10
}
]
}{
"_id": 2,
"favorites": {
"artist": "Miro",
"food": "meringue"
},
"finished": [
11,
25
],
"badges": [
"green"
],
"points": [
{
"points": 85,
"bonus": 20
},
{
"points": 64,
"bonus": 12
}
]
}{
"_id": 3,
"favorites": {
"artist": "Cassatt",
"food": "cake"
},
"finished": [
6
],
"badges": [
"blue",
"red"
],
"points": [
{
"points": 85,
"bonus": 8
},
{
"points": 55,
"bonus": 20
}
]
}{
"_id": 4,
"favorites": {
"artist": "Chagall",
"food": "chocolate"
},
"finished": [
5,
11
],
"badges": [
"red",
"black"
],
"points": [
{
"points": 53,
"bonus": 15
},
{
"points": 51,
"bonus": 15
}
]
}{
"_id": 5,
"favorites": {
"artist": "Noguchi",
"food": "nougat"
},
"finished": [
14,
6
],
"badges": [
"orange"
],
"points": [
{
"points": 71,
"bonus": 20
}
]
}{
"_id": 6,
"favorites": {
"food": "pizza",
"artist": "Picasso"
},
"finished": [
18,
12
],
"badges": [
"black",
"blue"
],
"points": [
{
"points": 78,
"b onus": 8
},
{
"points": 57,
"bonus": 7
}
]
}
我想檢索具有所有元素點= 85和獎金= 20。 查詢將是
db.temp2.find({"points":{"points":85,"bonus":20}})
它返回文檔ID爲：1和2
現在，如果我想檢索具有元件（分= 85和獎金= 20）且另一子文檔與{積分= 85和獎金> 10）。基本上，我想用ID檢索元素= 2
如果查詢
db.temp2.find({$and:[{"points":{"points":85,"bonus":20}},{"points":{"points":64,"bonus":{$gte:10}}}]}).pretty()
它沒有給出結果，而查詢
db.temp2.find({$and:[{"points":{"$elemMatch":{"points":85,"bonus":20}}},{"points":{"$elemMatch":{"points":64,"bonus":{$gte:10}}}}]})
給我ID = 2。
同樣的事情，我試着用花葯套
[
{
"name": "User1",
"tags": [
{
"k": "group",
"v": "test"
},
{
"k": "color",
"v": "blue"
}
]
},
{
"name": "User2",
"tags": [
{
"k": "group",
"v": "dev"
},
{
"k": "color",
"v": "blue"
}
]
},
{
"name": "User3",
"tags": [
{
"k": "group",
"v": "dev"
},
{
"k": "color",
"v": "red"
}
]
}
]
，如果你想找出其元素
"tags": [
{
"k": "group",
"v": "dev"
},
{
"k": "color",
"v": "blue"
}
]
查詢：
db.temp4.find({$and:[{"tags":{"k":"group","v":"dev"}},{"tags":{"k":"color","v":"blue"}}]})
和
db.temp4.find({$and:[{"tags":{"$elemMatch":{"k":"group","v":"dev"}}},{"tags":{"$elemMatch":{"k":"color","v":"blue"}}}]})
在這兩種情況下你都會得到迴應。
請幫我瞭解何時使用 $ elemMatch和「$」和「」。
在此先感謝。 對不起語法錯誤。