Question

尝试使用Linq加入。我该怎么用？左连接还是右连接？

     APPLICANT TABLE                         PROFILE TABLE
APPLICANT_ID|profile_id|Applicant_Name| |profile_id|Applicant_Name  
      1     |    NULL  |  RAY HEAVENS | |    1     | MARK LAPID
      2     |    NULL  |  BEN TULFO   | |    2     | SUPER MAN
      3     |     1    |      NULL    | |    3     | BRANDON KNIGHT
      4     |     2    |      NULL    | |
      5     |     3    |      NULL    | |

DESIRED OUTPUT: 

APPLICANT_ID | Applicant_Name
      1      |   RAY HEAVENS
      2      |   BEN TULFO
      3      |   MARK LAPID
      4      |   SUPERMAN
      5      |   BRANDON KNIGHT

这是我控制器中的代码：

var applicantList = (from a in context.Profiles 
                     join app in context.APPLICANTs
                     on a.PROFILE_ID equals app.Profile_id into output
                     from j in output.DefaultIfEmpty(new APPLICANT())
                     select j ).Take(1000).AsEnumerable();

                   applicantdata = applicantList.AsQueryable().OrderBy(v => v.APPLICANT_ID).ToList();


            if (applicantdata.Any())
            {
                Cache.Set("applicants", applicantdata, 30);
            }
        }
        return applicantdata;

    }

我希望有人可以推荐我使用或做什么。提前谢谢。

Answer 1

更新了错误：您需要创建一个包含所需属性的新类并将其返回。

    var applicantList = (from app in context.APPLICANTs
                         join a in context.Profiles
                         on app.Profile_id equals a.PROFILE_ID into output
                         from j in output.DefaultIfEmpty()
                         select new { APPLICANT_ID = app.APPLICANT_ID, Applicant_Name = (j == null ? app.Applicant_Name : j.Applicant_Name) }).Take(1000).AsEnumerable();

使用LINQ Entity-Framework进行LEFT JOIN或RIGHT JOIN

1 个答案: