Is there any efficiency difference in an explicit vs implicit inner join?
select * from
table a inner join table b
on a.id = b.id;
select a.*, b.*
from table a, table b
where a.id = b.id;
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 OUTER JOIN syntax as used in the question is still supported)