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POMixing implicit and explicit JOINs
 

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    <p>I am having a problem with Hibernate generating invalid SQL. Specifically, mixing and matching implicit and explicit joins. This seems to be an <a href="http://opensource.atlassian.com/projects/hibernate/browse/HHH-3388" rel="noreferrer">open bug</a>.</p> <p>However, I'm not sure <em>why</em> this is invalid SQL. I have come up with a small toy example that generates the same syntax exception.</p> <h2>Schema</h2> <pre><code>CREATE TABLE Employee ( employeeID INT, name VARCHAR(255), managerEmployeeID INT ) </code></pre> <h2>Data</h2> <pre><code>INSERT INTO Employee (employeeID, name) VALUES (1, 'Gary') INSERT INTO Employee (employeeID, name, managerEmployeeID) VALUES (2, 'Bob', 1) </code></pre> <h2>Working SQL</h2> <p>Both of these queries work. I realize there is a Cartesian product; that's intentional.</p> <p><em>Explicit JOIN:</em></p> <pre><code>SELECT e1.name, e2.name, e1Manager.name FROM Employee e1 CROSS JOIN Employee e2 INNER JOIN Employee e1Manager ON e1.managerEmployeeID = e1Manager.employeeID </code></pre> <p><em>Implicit JOIN:</em></p> <pre><code>SELECT e1.name, e2.name, e1Manager.name FROM Employee e1, Employee e2, Employee e1Manager WHERE e1.managerEmployeeID = e1Manager.employeeID </code></pre> <h2>Invalid SQL</h2> <p>This query does NOT work on MSSQL 2000/2008 or MySQL:</p> <pre><code>SELECT e1.name, e2.name, e1Manager.name FROM Employee e1, Employee e2 INNER JOIN Employee e1Manager ON e1.managerEmployeeID = e1Manager.employeeID </code></pre> <p>In MS2000, I get the error: </p> <blockquote> <p>The column prefix 'e1' does not match with a table name or alias name used in the query.</p> </blockquote> <p>In MySQL, the error is:</p> <blockquote> <p>Unknown column 'e1.managerEmployeeID' in 'on clause'.</p> </blockquote> <h2>Question(s)</h2> <ol> <li>Why is this syntax invalid?</li> <li><strong>Bonus:</strong> Is there a way to force Hibernate to use only explicit JOINs?</li> </ol> <hr>
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