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PODB : Circular dependency in the database
 

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  1. PODB : Circular dependency in the database
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    <p><strong>EDIT:</strong> This is a <a href="https://stackoverflow.com/questions/1451553/cascading-deletes-causing-multiple-cascade-paths">duplicate</a> I didn't find it at first. </p> <p>I am building a web-site for user-groups event management. </p> <pre><code>Members : Name, Id Events : DateTime, Topic, OrganizerId (from FK to Members table) EventRegistrations : MemberId (FK), EventId (FK) </code></pre> <p><em>Description (redundant) :</em><br> A member can create and event, and becomes this event's organizer.<br> Any member can register for an event, and a record in EventRegistrations is created. </p> <p><strong>The Problem:</strong><br> When I create PK-FK dependency between the tables, I get an error saying: </p> <blockquote> <p>Introducing FOREIGN KEY constraint 'reg_evt_fk' on table 'eventregistrations' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.</p> </blockquote> <p><strong>Question:</strong><br> What is a good way to deal with this? I have two solutions to begin with: </p> <ol> <li>Introduce 4th (associating) table "Organizers : MemberId -> EventId". </li> <li>Disable CASCADE DELETE on one of the dependencies, and do check programmatically before DELETE operations. </li> </ol> <p>I'm looking for suggestions or a feedback on the above. Extra explanations/comments are appreciated.</p> <p><em>Note</em>: DB is SQL Server 2008, but it shouldn't matter, I think.</p> <p><strong>EDIT:</strong> Suppose deleting an event <em>IS</em> required behavior (example is simplified).</p>
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    1. USCommunity
    1. USTHX-1138
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    1. COJust to be clear: creating the OrganizerId field gives you the circular dependency error?
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    2. COIt's probably "multiple cascade paths" not the circular dependency one. Exact error is: "Introducing FOREIGN KEY constraint 'reg_evt_fk' on table 'eventregistrations' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints."
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      1. USTHX-1138
 

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