SQL查询与联接到Linq查询

Question

我有这个疑问：

SELECT DISTINCT 
    responseInstanceID 
FROM 
    rRuleTriggerResponse rtr 
LEFT JOIN 
    rRuleTrigger rt ON rtr.ruleTriggerID = rt.ruleTriggerID 
LEFT JOIN 
    rRule r ON rt.ruleTriggerID = r.ruleTriggerID 
WHERE 
    r.ratingLogicVersion = '<<RatingLogicVersion>>' // RatingLogicVersion - e.g. "4.8" 

我需要将其转换到LINQ查询（C＃）（获得布尔值，如果responseInstanceID存在）

在C＃我有这个结构：

public partial class rResponseInstance : BaseEntity 
    { 
     public rResponseInstance() 
     { 
      this.rRuleTriggerResponses = new List<rRuleTriggerResponse>(); 
     } 

     [Key("rResponseInstance", true)] 
     public int responseInstanceID { get; set; } 
     [Key("rQuestionInstance")] 
     public int questionInstanceID { get; set; } 
     public virtual ICollection<rRuleTriggerResponse> rRuleTriggerResponses { get; set; } 
    } 

public partial class rRuleTriggerResponse : BaseEntity 
    { 
     [Key("rRuleTriggerResponse", true)] 
     public int ruleTriggerResponseID { get; set; } 
     [Key("rRuleTrigger")] 
     public int ruleTriggerID { get; set; } 
     [Key("rResponseInstance")] 
     public int responseInstanceID { get; set; } 
     public virtual rResponseInstance rResponseInstance { get; set; } 
     public virtual rRuleTrigger rRuleTrigger { get; set; } 
    } 

public partial class rRuleTrigger : BaseEntity 
    { 
     public rRuleTrigger() 
     { 
      this.rRules = new List<rRule>(); 
      this.rRuleTriggerResponses = new List<rRuleTriggerResponse>(); 
     } 

     [Key("rRuleTrigger", true)] 
     public int ruleTriggerID { get; set; } 
     public virtual ICollection<rRule> rRules { get; set; } 
     public virtual ICollection<rRuleTriggerResponse> rRuleTriggerResponses { get; set; } 
    } 

public partial class rRule : BaseEntity 
    { 
     [Key("rRule", true)] 
     public int ruleID { get; set; } 
     [Key("rRatingLogic")] 
     public string ratingLogicVersion { get; set; } 
     [Key("rRuleTrigger")] 
     public int ruleTriggerID { get; set; } 
     public virtual rRatingLogic rRatingLogic { get; set; } 
     public virtual rRuleTrigger rRuleTrigger { get; set; } 
    } 

对于查询，我只有一个对象 - rResponseInstance model。那么，是否有可能只用型号执行SQL查询？我很厉害的LINQ加入（

Answer 1

不要使用join子句的一切，让导航性能做的工作：

var ratingLogicVersion = "4.8"; 

var query = 
    db.rRuleTriggerResponses 
    .Where(resp => resp.rRuleTrigger.rRules 
         .Any(rule => ruler.ratingLogicVersion == ratingLogicVersion)) 
    .Select(resp => resp.responseInstanceID); 

注意，你不需要任何Distinct更多，因为结果乘以结果不见了（取而代之的是EXISTS）。