Explicit vs implicit SQL joins

Question

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; 

Answer 1

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

Answer 2

Personally I prefer the join syntax as its makes it clearer that the tables are joined and how they are joined. Try compare larger SQL queries where you selecting from 8 different tables and you have lots of filtering in the where. By using join syntax you separate out the parts where the tables are joined, to the part where you are filtering the rows.