MongoCollectionDistinct
MongoCollectionDistinct[MongoCollection[…],f]
obtain a list of distinct values for the field in the collection.
MongoCollectionDistinct[MongoCollection[…],field,query]
obtain a list of distinct values for the field for documents matching query.
更多信息和选项
- To use MongoCollectionDistinct, you first need to load MongoLink using Needs["MongoLink`"].
- MongoCollectionDistinct returns a List.
- MongoCollectionDistinct corresponds to the db.collection.distinct.
范例
基本范例 (1)
Connect to a new "WolframTestDistinct" collection in the "WolframTestDB" database:
Find the list of distinct items in the "dept" field:
Find the list of distinct items in the "sku" subfield of the "item" field:
Find the list of distinct items in the "sku" subfield of the "item" field from the set of documents whose "dept" field has value "A":
文本
Wolfram Research (2018)，MongoCollectionDistinct，Wolfram 语言函数，https://reference.wolfram.com/language/MongoLink/ref/MongoCollectionDistinct.html.
CMS
Wolfram 语言. 2018. "MongoCollectionDistinct." Wolfram 语言与系统参考资料中心. Wolfram Research. https://reference.wolfram.com/language/MongoLink/ref/MongoCollectionDistinct.html.
APA
Wolfram 语言. (2018). MongoCollectionDistinct. Wolfram 语言与系统参考资料中心. 追溯自 https://reference.wolfram.com/language/MongoLink/ref/MongoCollectionDistinct.html 年