LEFT JOIN or RIGHT JOIN using LINQ Entity-Framework

18,957

Updated for the error: You will need to create a new class with the required properties and return it.

    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();
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Enrique Gil
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Enrique Gil

Updated on June 04, 2022

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  • Enrique Gil
    Enrique Gil almost 2 years

    Trying joining using Linq. What should i use ? Left join or right join?

         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
    

    This is my code in my controller:

    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;
    
        }
    

    I hope someone can recommend me what to use or what to do. Thank you in advance.

    • Mathieu Guindon
      Mathieu Guindon almost 11 years
      I would believe .DefaultIfEmpty() translates into a LEFT JOIN, have you profiled it?
  • Enrique Gil
    Enrique Gil almost 11 years
    sir . . now im experiencing Exception Error 1 Cannot implicitly convert type 'System.Collections.Generic.List<AnonymousType#1>' to 'System.Collections.Generic.IEnumerable<Applicant.Models.APP‌​LICANT>'. An explicit conversion exists (are you missing a cast?) at applicantdata = applicantList.AsQueryable().OrderBy(v => v.APPLICANT_ID).ToList();
  • Enrique Gil
    Enrique Gil almost 11 years
    Sir @cheedep Thank you but now theres a new exception at applicantdata = applicantList.AsQueryable().OrderBy(v => v.APPLICANT_ID).ToList(); the new exception is NotSupported Exception was unhandled by user code The entity or complex type 'Model.APPLICANT' cannot be constructed in a LINQ to Entities query