mongodb sort limit和skip用法
检索数据可以使用sort()方法来对数据进行排序，指定排序字段，并使用1或-1来指定排序方式是升序或降序。类似于SQL语句中的order by语句。
可以使用limit()方法来读取指定数量的数据，还可以使用skip()方法来跳过指定数量的数据。对分页性能上面效率非常高。
1. 语法
>db.COLLECTION_NAME.find().sort({KEY:1})
>db.COLLECTION_NAME.find().limit(NUMBER)
>db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)
2. sort()
> db.mediaCollection.find().sort({"Tracklist":1}).toArray()[ { "_id" : ObjectId("5353462f93efef02c962da71"), "Type" : "Book", "Title" : "Definitive Guide to 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
> db.mediaCollection.find().sort({"Tracklist":1}).toArray()
[
{
"_id" : ObjectId("5353462f93efef02c962da71"),
"Type" : "Book",
"Title" : "Definitive Guide to MongoDB, the",
"ISBN" : "987-1-4302-3051-9",
"Publisher" : "Apress",
"Author" : [
"Membrey, Peter",
"Plugge, Eelco",
"Hawkins, Tim"
]
},
{
"_id" : ObjectId("5353462f93efef02c962da72"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind"
},
{
"_id" : ObjectId("5353463193efef02c962da73"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind",
"Tracklist" : [
{
"Track" : "1",
"Title" : "Smells like teen spirit",
"Length" : "5:02"
},
{
"Track" : "2",
"Title" : "In Bloom",
"Length" : "4:15"
}
]
}
]
> db.mediaCollection.find().toArray()
[
{
"_id" : ObjectId("5353462f93efef02c962da71"),
"Type" : "Book",
"Title" : "Definitive Guide to MongoDB, the",
"ISBN" : "987-1-4302-3051-9",
"Publisher" : "Apress",
"Author" : [
"Membrey, Peter",
"Plugge, Eelco",
"Hawkins, Tim"
]
},
{
"_id" : ObjectId("5353462f93efef02c962da72"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind"
},
{
"_id" : ObjectId("5353463193efef02c962da73"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind",
"Tracklist" : [
{
"Track" : "1",
"Title" : "Smells like teen spirit",
"Length" : "5:02"
},
{
"Track" : "2",
"Title" : "In Bloom",
"Length" : "4:15"
}
]
}
]
注意：如果指定的排序键不存在，那么数值将以它们插入的顺序升序返回。
3. limit()
该函数用来指定返回结果的最大数量。
> db.mediaCollection.find().limit(1).toArray()[ { "_id" : ObjectId("5353462f93efef02c962da71"), "Type" : "Book", "Title" : "Definitive Guide to MongoDB, the", "ISBN" : "987-1-4302-3051-9", "Publisher" : "Apress", "Author" : [ "Membrey, Peter", "Plugge, Eelco", "Hawkins, Tim" ] }]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
> db.mediaCollection.find().limit(1).toArray()
[
{
"_id" : ObjectId("5353462f93efef02c962da71"),
"Type" : "Book",
"Title" : "Definitive Guide to MongoDB, the",
"ISBN" : "987-1-4302-3051-9",
"Publisher" : "Apress",
"Author" : [
"Membrey, Peter",
"Plugge, Eelco",
"Hawkins, Tim"
]
}
]
4. skip()
跳过前面两条数据。
> db.mediaCollection.find().skip(2).toArray()[ { "_id" : ObjectId("5353463193efef02c962da73"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Title" : "Smells like teen spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
> db.mediaCollection.find().skip(2).toArray()
[
{
"_id" : ObjectId("5353463193efef02c962da73"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind",
"Tracklist" : [
{
"Track" : "1",
"Title" : "Smells like teen spirit",
"Length" : "5:02"
},
{
"Track" : "2",
"Title" : "In Bloom",
"Length" : "4:15"
}
]
}
]
5. 组合使用
> db.mediaCollection.find().sort({"Tracklist":1}).toArray()[ { "_id" : ObjectId("5353462f93efef02c962da71"), "Type" : "Book", "Title" : "Definitive Guide to MongoDB, the", "ISBN" : "987-1-4302-3051-9", "Publisher" : "Apress", "Author" : [ "Membrey, Peter", "Plugge, Eelco", "Hawkins, Tim" ] }, { "_id" : ObjectId("5353462f93efef02c962da72"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind" }, { "_id" : ObjectId("5353463193efef02c962da73"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Title" : "Smells like teen spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }]> db.mediaCollection.find().sort({"Tracklist":1}).limit(1).skip(1).toArray()[ { "_id" : ObjectId("5353462f93efef02c962da72"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind" }]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
> db.mediaCollection.find().sort({"Tracklist":1}).toArray()
[
{
"_id" : ObjectId("5353462f93efef02c962da71"),
"Type" : "Book",
"Title" : "Definitive Guide to MongoDB, the",
"ISBN" : "987-1-4302-3051-9",
"Publisher" : "Apress",
"Author" : [
"Membrey, Peter",
"Plugge, Eelco",
"Hawkins, Tim"
]
},
{
"_id" : ObjectId("5353462f93efef02c962da72"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind"
},
{
"_id" : ObjectId("5353463193efef02c962da73"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind",
"Tracklist" : [
{
"Track" : "1",
"Title" : "Smells like teen spirit",
"Length" : "5:02"
},
{
"Track" : "2",
"Title" : "In Bloom",
"Length" : "4:15"
}
]
}
]
> db.mediaCollection.find().sort({"Tracklist":1}).limit(1).skip(1).toArray()
[
{
"_id" : ObjectId("5353462f93efef02c962da72"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind"
}
]
6. 自然顺序$natural
> db.mediaCollection.find().sort( { $natural: -1 } ).toArray()[ { "_id" : ObjectId("5353463193efef02c962da73"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind", "Tracklist" : [ { "Track" : "1", "Title" : "Smells like teen spirit", "Length" : "5:02" }, { "Track" : "2", "Title" : "In Bloom", "Length" : "4:15" } ] }, { "_id" : ObjectId("5353462f93efef02c962da72"), "Type" : "CD", "Artist" : "Nirvana", "Title" : "Nevermind" }, { "_id" : ObjectId("5353462f93efef02c962da71"), "Type" : "Book", "Title" : "Definitive Guide to MongoDB, the", "ISBN" : "987-1-4302-3051-9", "Publisher" : "Apress", "Author" : [ "Membrey, Peter", "Plugge, Eelco", "Hawkins, Tim" ] }]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
> db.mediaCollection.find().sort( { $natural: -1 } ).toArray()
[
{
"_id" : ObjectId("5353463193efef02c962da73"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind",
"Tracklist" : [
{
"Track" : "1",
"Title" : "Smells like teen spirit",
"Length" : "5:02"
},
{
"Track" : "2",
"Title" : "In Bloom",
"Length" : "4:15"
}
]
},
{
"_id" : ObjectId("5353462f93efef02c962da72"),
"Type" : "CD",
"Artist" : "Nirvana",
"Title" : "Nevermind"
},
{
"_id" : ObjectId("5353462f93efef02c962da71"),
"Type" : "Book",
"Title" : "Definitive Guide to MongoDB, the",
"ISBN" : "987-1-4302-3051-9",
"Publisher" : "Apress",
"Author" : [
"Membrey, Peter",
"Plugge, Eelco",
"Hawkins, Tim"
]
}
]
页:
[1]