MongoDb在C#中查询

最新推荐文章于 2023-04-11 15:47:27 发布

ArmyFai

最新推荐文章于 2023-04-11 15:47:27 发布

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分类专栏： C# 文章标签： mongodb c# query table sql c

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本文介绍如何使用MongoDB进行高效的数据查询操作，包括条件筛选、字段选择、排序限制等技巧，并展示了如何将SQL查询转换为MongoDB查询语句。

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    /*---------------------------------------------
             * sql : SELECT * FROM table 
             *---------------------------------------------
             */
            MongoCursor<Person> p = mongoCollection.FindAllAs<Person>();

            /*---------------------------------------------
             * sql : SELECT * FROM table WHERE Uid > 10 AND Uid < 20
             *---------------------------------------------
             */
            QueryDocument query = new QueryDocument();
            BsonDocument b = new BsonDocument();
            b.Add("$gt", 10);
            b.Add("$lt", 20);
            query.Add("Uid", b);

            MongoCursor<Person> m = mongoCollection.FindAs<Person>(query);

            /*-----------------------------------------------
             * sql : SELECT COUNT(*) FROM table WHERE Uid > 10 AND Uid < 20
             *-----------------------------------------------
             */
            long c = mongoCollection.Count(query);

            /*-----------------------------------------------
            * sql : SELECT Name FROM table WHERE Uid > 10 AND Uid < 20
            *-----------------------------------------------
            */
            QueryDocument query = new QueryDocument();
            BsonDocument b = new BsonDocument();
            b.Add("$gt", 10);
            b.Add("$lt", 20);
            query.Add("Uid", b);
            FieldsDocument f = new FieldsDocument();
            f.Add("Name", 1);

            MongoCursor<Person> m = mongoCollection.FindAs<Person>(query).SetFields(f);
            /*-----------------------------------------------
            * sql : SELECT * FROM table ORDER BY Uid DESC LIMIT 10,10
            *-----------------------------------------------
            */
            QueryDocument query = new QueryDocument();
            SortByDocument s = new SortByDocument();
            s.Add("Uid", -1);//-1=DESC

            MongoCursor<Person> m = mongoCollection.FindAllAs<Person>().SetSortOrder(s).SetSkip(10).SetLimit(10);