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PONHibernate is producing SQL with a bad join
 

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    <p>I have an NHibernate Linq query which isn't working how I would expect.</p> <p>The problem seems to come from using a nullable int column from a left joined table in the where clause. This is causing the join to act like an inner join.</p> <pre><code>var list = this.WorkflowDiaryManager.WorkflowActionRepository.All .Fetch(x =&gt; x.CaseView) .Fetch(x =&gt; x.WorkflowActionType) .ThenFetchMany(x =&gt; x.WorkflowActionPriorityList) .Where(x =&gt; x.AssignedUser.Id == userId || x.CaseView.MooseUserId == userId) </code></pre> <p>The SQL produced by this looks like (from the join onwards - you don't need to see all the selects)</p> <pre><code>from Kctc.WorkflowAction workflowac0_ left outer join Kctc.WorkflowCaseView workflowca1_ on workflowac0_.CaseId=workflowca1_.CaseId left outer join Kctc.WorkflowActionType workflowac2_ on workflowac0_.WorkflowActionTypeId=workflowac2_.WorkflowActionTypeId left outer join Kctc.WorkflowActionPriority workflowac3_ on workflowac2_.WorkflowActionTypeId=workflowac3_.WorkflowActionTypeId ,Kctc.WorkflowCaseView workflowca4_ where workflowac0_.CaseId=workflowca4_.CaseId and (workflowac0_.AssignedUser=@p0 or workflowca4_.[MooseUserId]=@p1); @p0 = 1087 [Type: Int32 (0)], @p1 = 1087 [Type: Int32 (0)] </code></pre> <p>So the part that is causing the problem is line 5 of the snippet above. As you can see, NHibernate is trying to do an 'old-school' join on my WorkflowCaseView View. This causes the query to exclude otherwise valid actions which do not have a CaseId in the WorkflowAction table.</p> <p>Could anyone explain why NHibernate is writing this SQL, and how I might encourage it to produce a better query?</p> <p>Thanks!</p> <p>Important bits from WorkflowActionMap</p> <pre><code> Table("Kctc.WorkflowAction"); Id(x =&gt; x.Id).GeneratedBy.Identity().Column("WorkflowActionId"); References(x =&gt; x.WorkflowActionType).Column("WorkflowActionTypeId").Unique(); References(x =&gt; x.CompletedBy).Column("CompletedBy"); References(x =&gt; x.CaseView).Column("CaseId").Not.Update().Unique(); References(x =&gt; x.AssignedUser).Column("AssignedUser"); </code></pre> <p>Important bits from WorkflowCaseViewMap</p> <pre><code> Table("Kctc.WorkflowCaseView"); Id(x =&gt; x.Id).Column("CaseId"); Map(x =&gt; x.MooseUserId).Nullable(); </code></pre> <p>Looking at this, I wonder if I should have a HasMany going back the other way...</p> <p>EDIT. Doesn't seem to help</p>
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