Is there any efficiency difference in an explicit vs implicit inner join?
For example:

SELECT * FROM
table a INNER JOIN table b
ON a.id = b.id;

vs.

SELECT a.*, b.*
FROM table a, table b
WHERE a.id = b.id;

12 Answers
12

Performance wise, they are exactly the same (at least in SQL Server).

PS: Be aware that the IMPLICIT OUTER JOIN syntax is deprecated since SQL Server 2005. (The IMPLICIT INNER JOIN syntax as used in the question is still supported)

Deprecation of “Old Style” JOIN Syntax: Only A Partial Thing

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