Linq Sub Query (SELECT в SELECT) - PullRequest
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Linq Sub Query (SELECT в SELECT)

1 голос
/ 15 декабря 2011

У меня проблема с собственным подзапросом в MySQL. Код SQL:

Структура БД:

tbl_urunler_kod
id , код
- 1, pkod1
- 2, pkod2
- 3, pkod3

tbl_urunler
id , kod_id
- 1, 1
- 2, 2
- 3, 3
- 4, ноль
- 5, ноль
- 6, ноль
- 7, ноль
- 8, ноль
- 9, ноль

SELECT (SELECT k.kod FROM tbl_urunler_kod k WHERE k.id=t.kod_id) AS kod FROM tbl_urunler t

дает 9 записей.

Я пробую это, 

 var SQL = (from p in SME.tbl_urunler
                   from k in SME.tbl_urunler_kod
                              where k.id == p.kod_id
                   select new
                   {
                       kod = k.kod
                   });

возвращает только 3 записи. Потому что tbl_urunler_kod получил только не ноль 3 записи. Другие 6 записей являются нулевыми. Я хочу увидеть все записи. Как я могу это сделать.

И я попробую это; 

var SQL2 = (from p in SME.tbl_urunler
                       select new
                       {
                           kod = (from k in SME.tbl_urunler_kod where k.id == p.kod_id select new { k.kod })
                       });

Это дает эту ошибку; 

'System.Data.Common.Internal.Materialization.CompensatingCollection`1[f__AnonymousType0`1[System.String]]' türündeki nesne 'System.String' türüne atılamadı.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.InvalidCastException: 'System.Data.Common.Internal.Materialization.CompensatingCollection`1[f__AnonymousType0`1[System.String]]' türündeki nesne 'System.String' türüne atılamadı.

Спасибо за вашу помощь.

Ответы [ 3 ]

1 голос
/ 15 декабря 2011

это лямбда-выражение LingtoSql 

    var query = SME.tbl_urunler.Where
                (x=>x.tbl_urunler_kod.id == x.kod_id  || 
                x.kod_id == null).Select(x=>new {x.id})
1 голос
/ 16 декабря 2011

Я был создан немного симулатин для этого. Пожалуйста, посмотрите результаты; 

public class tbl_urunler_kod
{
    public int ID { get; set; }
    public string Kod { get; set; }
    public tbl_urunler_kod() { }
    public tbl_urunler_kod(int _ID, string _Kod)
    {
        _ID = ID;
        _Kod = Kod;
    }
}

public class tbl_urunler
{
    public int ID { get; set; }
    public string Adi { get; set; }
    public int KodID { get; set; }
    public tbl_urunler() { }
    public tbl_urunler(int _ID, string _Adi, int _KodID)
    {
        _ID = ID;
        _Adi = Adi;
        _KodID = KodID;
    }
}

public List<tbl_urunler_kod> L_tbl_urunler_kod = new List<tbl_urunler_kod>();
public List<tbl_urunler> L_tbl_urunler = new List<tbl_urunler>();

protected void Page_Load(object sender, EventArgs e)
{
    Fill();
    Result1();
    Result2();
    Result3();
    Result4();
    Result5(); //Its working
    Result6(); //Its working
    Result7(); //Its working
}

public void Fill()
{
    #region tbl_urunler_kod filling
    L_tbl_urunler_kod.Add(new tbl_urunler_kod { ID = 1, Kod = "Kod_1" });
    L_tbl_urunler_kod.Add(new tbl_urunler_kod() { ID = 2, Kod = "Kod_2" });
    L_tbl_urunler_kod.Add(new tbl_urunler_kod() { ID = 3, Kod = "Kod_3" });
    #endregion

    #region tbl_urunler filling
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_1", ID = 1, KodID = 1 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_2", ID = 2, KodID = 2 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_3", ID = 3, KodID = 3 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_4", ID = 4 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_5", ID = 5 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_6", ID = 6 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_7", ID = 7 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_8", ID = 8 });
    L_tbl_urunler.Add(new tbl_urunler() { Adi = "Urun_9", ID = 9 });
    #endregion
}

public void Result1()
{
    Response.Write("<h1>Result 1</h1>");

    var SQL = (from p in L_tbl_urunler
               from k in L_tbl_urunler_kod
               where k.ID == p.KodID
               select new
               {
                   p.Adi,
                   kod = k.Kod
               }); //result count = 3 record;

    foreach (var i in SQL)
    {
        Response.Write(i.Adi + " - " + i.kod + "<br/>");
    }

    Response.Write("<br/><hr/>");
}

public void Result2()
{
    Response.Write("<h1>Result 2</h1>");

    var SQL = (from p in L_tbl_urunler
               from k in L_tbl_urunler_kod
               where k.ID == p.KodID || p.KodID == 0
               select new
               {
                   p.Adi,
                   kod = k.Kod
               }); //result count = 21 record;

    foreach (var i in SQL)
    {
        Response.Write(i.Adi + " - " + i.kod + "<br/>");
    }

    Response.Write("<br/><hr/>");
}

public void Result3()
{
    Response.Write("<h1>Result 3</h1>");

    var SQL = (from p in L_tbl_urunler
               let LKod = L_tbl_urunler_kod.Where(k => k.ID == p.KodID).Select(x => x.Kod)
               select new
               {
                   p.Adi,
                   kod = LKod
               }); //result count = 9 record;

    foreach (var i in SQL)
    {
        Response.Write(i.Adi + " - " + i.kod + "<br/>");
        //System.Linq.Enumerable+WhereSelectListIterator`2[test+tbl_urunler_kod,System.String]
    }

    Response.Write("<br/><hr/>");
}

public void Result4()
{
    Response.Write("<h1>Result 4</h1>");

    var SQL = (from p in L_tbl_urunler
               select new
               {
                   p.Adi,
                   kod = (from k in L_tbl_urunler_kod where k.ID == p.KodID select new { k.Kod })
               }); //result count = 9 record;

    foreach (var i in SQL)
    {
        Response.Write(i.Adi + " - " + i.kod + "<br/>");
        //System.Linq.Enumerable+WhereSelectListIterator`2[test+tbl_urunler_kod,<>f__AnonymousType3`1[System.String]]
    }

    Response.Write("<br/><hr/>");
}

public void Result5()
{
    Response.Write("<h1>Result 5</h1>");

    var SQL = (from p in L_tbl_urunler
               select new
               {
                   p.Adi,
                   kod = L_tbl_urunler_kod.Where(k => k.ID == p.KodID).Select(x => x.Kod).FirstOrDefault()
               }); //result count = 9 record;

    foreach (var i in SQL)
    {
        Response.Write(i.Adi + " - " + i.kod + "<br/>");
    }

    Response.Write("<br/><hr/>");
}

public void Result6()
{
    Response.Write("<h1>Result 6</h1>");

    var SQL = (from p in L_tbl_urunler
               select new
               {
                   p.Adi,
                   kod = (from k in L_tbl_urunler_kod where k.ID == p.KodID select new { k.Kod }).FirstOrDefault()
               }); //result count = 9 record;

    foreach (var i in SQL)
    {
        Response.Write(i.Adi + " - " + i.kod + "<br/>");
    }

    Response.Write("<br/><hr/>");
}

public void Result7()
{
    Response.Write("<h1>Result 7</h1>");

    var SQL = (from p in L_tbl_urunler
               let LKod = L_tbl_urunler_kod.Where(k => k.ID == p.KodID).Select(x => x.Kod).FirstOrDefault()
               select new
               {
                   p.Adi,
                   kod = LKod
               }); //result count = 9 record;

    foreach (var i in SQL)
    {
        Response.Write(i.Adi + " - " + i.kod + "<br/>");
    }

    Response.Write("<br/><hr/>");
}

Результат 1 

Urun_1 - Kod_1
Urun_2 - Kod_2
Urun_3 - Kod_3

Результат 2 

Urun_1 - Kod_1
Urun_2 - Kod_2
Urun_3 - Kod_3
Urun_4 - Kod_1
Urun_4 - Kod_2
Urun_4 - Kod_3
Urun_5 - Kod_1
Urun_5 - Kod_2
Urun_5 - Kod_3
Urun_6 - Kod_1
Urun_6 - Kod_2
Urun_6 - Kod_3
Urun_7 - Kod_1
Urun_7 - Kod_2
Urun_7 - Kod_3
Urun_8 - Kod_1
Urun_8 - Kod_2
Urun_8 - Kod_3
Urun_9 - Kod_1
Urun_9 - Kod_2
Urun_9 - Kod_3

Результат 3 

Urun_1 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_2 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_3 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_4 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_5 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_6 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_7 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_8 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]
Urun_9 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,System.String]

Результат 4 

Urun_1 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_2 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_3 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_4 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_5 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_6 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_7 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_8 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]
Urun_9 - System.Linq.Enumerable+WhereSelectListIterator2[test+tbl_urunler_kod,<>f__AnonymousType31[System.String]]

Результат 5 

Urun_1 - Kod_1  
Urun_2 - Kod_2  
Urun_3 - Kod_3  
Urun_4 -  
Urun_5 -  
Urun_6 -  
Urun_7 -  
Urun_8 -  
Urun_9 -

Результат 6 

Urun_1 - { Kod = Kod_1 }  
Urun_2 - { Kod = Kod_2 }  
Urun_3 - { Kod = Kod_3 }  
Urun_4 -  
Urun_5 -  
Urun_6 -  
Urun_7 -  
Urun_8 -  
Urun_9 -

Результат 7 

Urun_1 - Kod_1  
Urun_2 - Kod_2  
Urun_3 - Kod_3  
Urun_4 -  
Urun_5 -  
Urun_6 -  
Urun_7 -  
Urun_8 -  
Urun_9 -

Спасибо.

1 голос
/ 15 декабря 2011

Вы пробовали: 

var SQL = (from p in SME.tbl_urunler
               from k in SME.tbl_urunler_kod
                          where k.id == p.kod_id || p.kod_id == null
               select new
               {
                   kod = k.kod
               });

Обновление вот что я могу понять из ваших комментариев: 

var q = from u in SME.tbl_urunler
    join k in SME.tbl_urunler_kod on u.kod_id equals k.id into JoinedUK
    from k in joinedUK.DefaultIfEmpty()
    select new
    {
        id = u.id,  
        kod = k != null ? k.kod : null
    }
...