Question
Which of the following joins will produce better performance?
ANSI JOIN Syntax
SELECT fname, lname, department
FROM names INNER JOIN departments ON names.employeeid = departments.employeeid
Former Microsoft JOIN Syntax
SELECT fname, lname, department
FROM names, departments
WHERE names.employeeid = departments.employeeid
Answer
SQL Server supports two variations of performing JOINs: the ANSI JOIN syntax and the former Microsoft JOIN syntax. Both produce identical results and identical performance. There is no performance reasons to use one form of the JOIN over the other.
On the other hand, there are two good reasons why you should use the ANSI JOIN syntax over the former Microsoft JOIN syntax. First, it is more portable because it is the ANSI standard, and second, because eventually Microsoft may eliminate support of the former JOIN syntax.
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