Question

我在db中有三个表，对应于代码中的实体。（为简单起见，我将这些课程搞砸了）

public class Current{
    [Key]
    public int CurrentId {get; set;}

    [Required]
    public int TableKeyId {get; set;}

    public string Value {get; set;}
}

public class Promotion{
    [Key]
    public int PromtionId {get; set;}

    [Required]
    public int TableKeyId {get; set;}

    public string Value {get; set;}
}

public class TableKey{
    [Key]
    public int TableKeyId {get;set;}

    [Required]
    public string PlanCode {get;set;}

    [Required]
    public byte Environment {get;set;}

    [Required]
    public byte FileId {get;set;}

    [Required]
    public string TableNumber {get;set;}

}

（Current和Promotion都有TableKeyId外键属性）。

我需要做的是从所有三个存储库中取出检索Currents和Promotions获取它们的值和TableKey属性。 我需要所有促销活动（如果它们存在）以及其TableKeyId与促销活动中的任何TableKeyId不相等的电流。我尝试使用以下查询完成此操作：

var query = (from c in this.currentRepository.Query()
                     join t in this.tableKeyRepository.All() on c.TableKeyId equals t.TableKeyId
                     join p in this.promotionRepository.Query() on c.TableKeyId equals p.TableKeyId into pc
                     from p in pc.DefaultIfEmpty()
                     where (t.PlanCode == command.PlanCode && t.Environment == command.Environment)
                     select new Temptable
                     {
                         TableNumber = t.TableNumber,
                         PlanCode = t.PlanCode,
                         FileId = t.FileId,
                         Value = (p == null ? c.Value : p.Value),
                         TableKeyId = c.TableKeyId
                     });

此查询几乎有效，除非存在具有与具有相同TableKeyId的Current不对应的TableKeyId的Promotion，否则它将不会检索它们，因为它是左外连接。我知道我可以使用多个查询来完成它，但我真的想要一个查询。另外请记住，每个表可能有大约1百万条记录，所以我必须优化查询。

所以，如果我有以下内容：

TableKeys

TableKeyId,PlanCode,Environment,FileId,TableNumber
--------------------------------------------------
1,"001",2,"PFT","A1234"
2,"001",2,"PFT","A1235"
3,"001",2,"PFT","A1236"
4,"001",2,"PFT","A1237"

电流

CurrentId,TableKeyId,Value
--------------------------
1,1,"A"
2,2,"B"
3,4,"C"

促销

PromotionId,TableKeyId,Value
---------------------------
1,1,"G"
2,2,"H"
3,3,"I"

如果我的查询中环境为2且PlanCode为“001”，我希望结果集为

TableKeyId,PlanCode,Environment,FileId,TableNumber,Value
--------------------------------------------------------
1,"001",2,"PFT","A1234","G"
2,"001",2,"PFT","A1235","H"
3,"001",2,"PFT","A1236","I"
4,"001",2,"PFT","A1237","C"

我非常感谢所有反馈：）

谢谢！

C＃LINQ查询项目并连接两个不同实体的序列

0 个答案: