相交两个列表<>

Question

我编辑我的帖子,因为让我们假设3个方法从数据库表表中返回行是:docTags,tags和docs docTags是中间表一个docs(文档)可以有很多标签,一个标签可以属于多个docs我怎么能得到: TagKey ="123"其中docTags.Add(new Configuration(1,1)); 课程{

    static void Main(string[] args)
    {

    }
}

public class Configuration
{
    public  int  DocID { get; set; }
    public int TagID { get; set; }
    public string Name { get; set; }
    public string DocKey { get; set; }
    public string TagKey { get; set; }

    public Configuration(int _docId,string _name, string _docKey)
    {
        DocID = _docId;
        Name = _name;
        DocKey = _docKey;
    }
    public Configuration(int _tagId,string name, string _dockey,string _tagKey)
    {
        TagID = _tagId;
        Name = name;
        TagKey = _tagKey;
    }
    public Configuration(int _tagId, int _docId)
    {
        TagID = _tagId;
        DocID = _docId;
    }
    public static List<Configuration> getDocType()
    {
        List<Configuration> docs = new List<Configuration>();
        docs.Add(new Configuration(1,"contract", "xxx"));
        docs.Add(new Configuration(2,"Action", "yyy"));
        return docs;
    }

    public static List<Configuration> getTagName()
    {
        List<Configuration> tags = new List<Configuration>();
        tags.Add(new Configuration( 1,"contractid", "123"));
        tags.Add(new Configuration(2,"SuperDuper", "332123"));
        tags.Add(new Configuration(22, "rama", "yyy"));
        tags.Add(new Configuration(32, "aktiv",  "123456"));
        tags.Add(new Configuration(42, "data ","xx764fhx"));
        return tags;

    }
    public static List<Configuration> getDocTags()
    {
        List<Configuration> docTags = new List<Configuration>();
        docTags.Add(new Configuration(1, 2));
        docTags.Add(new Configuration(1, 1));
        docTags.Add(new Configuration(1, 22));
        docTags.Add(new Configuration(2, 2));
        docTags.Add(new Configuration(2, 32));
        return docTags;
    }        
}

}

Answer 1

你想要一个Join:

var commonUsers = (from t in tags
                  join d in docs on t.DocKey equals d.DocKey
                  select t)
                  .Distinct();  // to remove duplicates

或者另一种方式

var commonUsers = tags.Where(t => docs.Any(d => d.DocKey == t.DocKey));

第二种方法较短,但第一种方法可能表现更好.