Question

在我的mongodb中，我收藏的很少，我想通过使用pymongo比较集合1和集合2来创建一个新的集合。

我希望获得第三个集合，对于每个主题，Prof_name查找collection2中的匹配主题以及特定时间戳之间的UUID和UUID_count

Collection 1 :
Object id       timestamp                          Prof_Name   subjects1 
abc67478898k  ISODate("2018-01-03T09:26:37.541Z")   ABDC      "sub1, sub2, sub3"
jjjjjjjjjj    ISODate("2018-01-03T09:26:37.541Z")   XYZ       "sub2, sub4, sub8"

Collection 2 :
Object id   timestamp               UUID   subjects2            rating score
3333333    ISODate("2018-01-03TZ")  7897  "sub1,sub4, sub7"     7      10
444444     ISODate("2018-01-03TZ")  4532   "sub2"               4      6
777777     ISODate("2018-01-03TZ")  7876  "sub1,sub2,sub3"      8      8
1111111    ISODate("2018-01-03TZ")   654   "sub1,sub3"          7      8

Collection 3 :

 objectid  Prof_name subjects_list  UUID_list           UUID-count subject_count
    12       ABDC      sub1,sub2,sub3 7897,4532,7876,654  4            3
    34       XYZ       sub2,sub4,sub8 7897,4532,7876      2            3

Answer 1

您可以在3.6中尝试以下聚合。

以下代码将cExp : a -> (a -> b) -> b cExp cm cn = cn cm字符串拆分为字符串值数组，然后$lookup过滤subjects1文档以匹配主题并输出collection_2。

UUID上的Prof_name个$addToSet文件，UUID subjects1和UUID后跟$group来计算subjects1和

db.collection_1.aggregate([
{"$addFields":{"subjects1":{"$split":["$subjects1",", "]}}},
{"$unwind":"$subjects1"},
{"$lookup":{
  "from":"collection_2",
  "let":{"subjects1":"$subjects1"},
  "pipeline":[
    {"$addFields":{"subjects2":{"$split":["$subjects2",","]}}},
    {"$match":{"$expr":{"$in":["$$subjects1","$subjects2"]}}},
    {"$project":{"UUID":1,"_id":0}}
  ],
  "as":"ref_data"}},
{"$unwind":{"path":"$ref_data","preserveNullAndEmptyArrays":true}},
{"$group":{
  "_id":"$Prof_Name",
  "subjects_list":{"$addToSet":"$subjects1"},
  "UUID_list":{"$addToSet":"$ref_data.UUID"}}},
{"$addFields":{
  "Prof_name":"$_id",
  "UUID_count":{"$size":"$UUID_list"},
  "subject_count":{"$size":"$subjects_list"}}},
{"$project":{"_id":0}},
{"$out":"collection_3"}
])

。

$size将回复写入新收藏。

$names = ['my name', 'another name'];

if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

$sql = "SELECT * FROM `clients` WHERE `name` IN ('".implode("','",$names)."') ORDER BY id DESC";

$result = $conn->query($sql);

while($row = $result->fetch_assoc()) {
    print_r($row);
}

$conn->close();

MongoDB比较两个集合并获得第三个集合

1 个答案: