Actually, as I remember, in old systems, your 2nd example should be: [#4135132@0 -ROLIA.NET 相约加拿大网上社区 之 枫下论坛 & 枫下部落, 枫下论坛主坛 ]
Actually, as I remember, in old systems, your 2nd example should be:
by
registereduser
(立牌坊)
at
2007.12.20 21:59
(#4135132@0)
SELECT *
FROM a, b
WHERE a.c1 = b.c1 AND a.c2 = b.c2
This old syntex is very unbilgous and I guess it first generate big base then narrow down as a result. A shamful history of SQL.
In some systems, condition used for join can be only one. You can not use AND or OR within the condition for JOIN. An example for sure is NATURAL JOIN in Oracle, no OR or AND is allows.