查詢,無論是關係型數據庫還是mongodb這種nosql,都是使用比較多的,大部分操作都是讀的操作。
mongodb的查詢方式很多種,下面只列了一些常用的,比如:
1.=查詢
2.模糊查詢
3.大於小於範圍查詢
4.in查詢
5.or查詢
6.查詢一條,查詢全部
7.自己慢慢學習...
根據作者查詢所有符合條件的數據,返回List<Article>
Query query = Query.query(Criteria.where("author").is("yinjihuan"));
List<Article> articles = mongoTemplate.find(query, Article.class);
只查詢符合條件的第一條數據,返回Article對象
query = Query.query(Criteria.where("author").is("yinjihuan"));
Article article = mongoTemplate.findOne(query, Article.class);
查詢集合中所有數據,不加條件
articles = mongoTemplate.findAll(Article.class);
查詢符合條件的數量
query = Query.query(Criteria.where("author").is("yinjihuan"));
long count = mongoTemplate.count(query, Article.class);
根據主鍵ID查詢
article = mongoTemplate.findById(new ObjectId("57c6e1601e4735b2c306cdb7"), Article.class);
in查詢
List<String> authors = Arrays.asList("yinjihuan", "jason");
query = Query.query(Criteria.where("author").in(authors));
articles = mongoTemplate.find(query, Article.class);
ne(!=)查詢
query = Query.query(Criteria.where("author").ne("yinjihuan"));
articles = mongoTemplate.find(query, Article.class);
lt(<)查詢訪問量小於10的文章
query = Query.query(Criteria.where("visitCount").lt(10));
articles = mongoTemplate.find(query, Article.class);
範圍查詢,大於5小於10
query = Query.query(Criteria.where("visitCount").gt(5).lt(10));
articles = mongoTemplate.find(query, Article.class);
模糊查詢,author中包含a的數據
query = Query.query(Criteria.where("author").regex("a"));
articles = mongoTemplate.find(query, Article.class);
數組查詢,查詢tags裏數量爲3的數據
query = Query.query(Criteria.where("tags").size(3));
articles = mongoTemplate.find(query, Article.class);
or查詢,查詢author=jason的或者visitCount=0的數據
query = Query.query(Criteria.where("").orOperator(
Criteria.where("author").is("jason"),
Criteria.where("visitCount").is(0)));
articles = mongoTemplate.find(query, Article.class);
作者:尹吉歡
鏈接:https://www.jianshu.com/p/502dbdb7613e
來源:簡書