C# 查询MongoDB数据

更新时间：2022-12-21 09:23

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实体类

public class User
{
    public MongoDB.Bson.ObjectId Id { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

查询所有数据和总个数

public void Read()
{                                       //帐号 lqwvje 密码 123456
    MongoClient client = new MongoClient("mongodb://lqwvje:123456@192.168.1.242:27017");
    //获取database
    IMongoDatabase mydb = client.GetDatabase("myDB");
    //获取collection
    IMongoCollection<User> collection = mydb.GetCollection<User>("user");
    FilterDefinitionBuilder<User> builderFilter = Builders<User>.Filter;
    //查询所有数据
    List<User> result = collection.Find(builderFilter.Empty).ToList();
    //查询总个数
    var count = collection.Find(builderFilter.Empty).CountDocuments();
}

条件查询

按条件查询 Name="张三"

public void Read()
{
    MongoClient client = new MongoClient("mongodb://lqwvje:123456@192.168.1.242:27017");
    //获取database
    IMongoDatabase mydb = client.GetDatabase("myDB");
    //获取collection
    IMongoCollection<User> collection = mydb.GetCollection<User>("user");
    FilterDefinition<User> builderFilter = Builders<User>.Filter.Eq(u => u.Name, "张三");
    //查询Name = 张三
    List<User> result = collection.Find(builderFilter).ToList();
}

C#驱动MongoDB官方中查询条件Query用法

• Query.All("name", "a", "b");//通过多个元素来匹配数组
• Query.And(Query.EQ("name", "a"), Query.EQ("title", "t"));//同时满足多个条件
• Query.Eq("name", "a");//等于
• Query.Exists("type", true);//判断键值是否存在
• Query.Gt("value", 2);//大于>
• Query.Gte("value", 3);//大于等于>=
• Query.In("name", "a", "b");//包括指定的所有值,可以指定不同类型的条件和值
• Query.Lt("value", 9);//小于<
• Query.Lte("value", 8);//小于等于<=
• Query.Mod("value", 3, 1);//将查询值除以第一个给定值,若余数等于第二个给定值则返回该结果
• Query.Ne("name", "c");//不等于
• Query.Nor(Array);//不包括数组中的值
• Query.Not("name");//元素条件语句
• Query.NotIn("name", "a", 2);//返回与数组中所有条件都不匹配的文档
• Query.Or(Query.EQ("name", "a"), Query.EQ("title", "t"));//满足其中一个条件
• Query.Size("name", 2);//给定键的长度
• Query.Type("_id", BsonType.ObjectId );//给定键的类型
• Query.Where(BsonJavaScript);//执行JavaScript
• Query.Matches("Title",str);//模糊查询 相当于sql中like -- str可包含正则表达式

排序分页查询

public void Read()
{
    MongoClient client = new MongoClient("mongodb://lqwvje:123456@192.168.1.242:27017");
    //获取database
    IMongoDatabase mydb = client.GetDatabase("myDB");
    //获取collection
    IMongoCollection<User> collection = mydb.GetCollection<User>("user");
    FilterDefinitionBuilder<User> builderFilter = Builders<User>.Filter;
    //分页 排序查询 SortBy升序    SortByDescending 降序
    List<User> result = collection.Find(builderFilter.Empty).SortByDescending(u=>u.Id).Skip(0).Limit(10).ToList();
}