vsarade (9/18/2012)
When executing the query with adding the FULL JOIN with where clause like below -SELECT Professor.Id AS [Professor.Id], Professor.ProfessorName,
CASE Professor.HasTenure WHEN 1 THEN 'True' WHEN 0 THEN 'False' ELSE NULL END AS [Has Tenure],
Class.ProfessorId AS [Class.ProfessorId], Class.ClassName,
Class.ClassYear, Class.ClassSemester
FROM Professor
FULL JOIN Class
ON Professor.Id = Class.ProfessorId AND Class.ClassYear >= 2011
WHERE Professor.HasTenure = 'True'
Then it is giving same results as adding LEFT OUTER JOIN.
Not really surprising. This is for the same reason that putting the "Class.ClassYear = 2011" condition into the where clause eliminates the effect of the LEFT OUTER JOIN and makes it act like an INNER JOIN. Because the condition "Professor.HasTenure = 'True'" is in the WHERE clause it will eliminate all of the entries where HasTenure is NULL. In other words it is eliminating all of the entries that the difference between FULL and OUTER join caused.
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