与Joins进入Linq查询的SQL查询

Question

I have this query :

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"

I need to transform it to Linq query (C#) (get bool value if responseInstanceID exists)

In C# I have this structure :

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; }
    }

For query I just have one object - rResponseInstance model . So, Is it possible to execute SQL query only with model ? I am badly with linq joins.(

Answer 1

Don't use the join clause at all, let the navigation properties do the job:

var ratingLogicVersion = "4.8";

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

Note that you don't need the Distinct any more, because the join that multiplied the results is gone (replaced by an EXISTS ).