Re: [Phpwiki-talk] Wanted Pages SQL Problem

[William L. <le...@k2...>]

I composed this message once before but it seems to have gotten lost in 
the ether. I ended up figuring this one out... I got Google lucky.

According to http://dev.mysql.com/doc/refman/5.0/en/join.html:
 
<Quote>
INNER JOIN| and |,| (comma) are semantically equivalent in the absence 
of a join condition: both produce a Cartesian product between the 
specified tables (that is, each and every row in the first table is 
joined to each and every row in the second table).

However, the precedence of the comma operator is less than than of 
|INNER JOIN|, |CROSS JOIN|, |LEFT JOIN|, and so on. If you mix comma 
joins with the other join types when there is a join condition, an error 
of the form |Unknown column '/|col_name|/' in 'on clause'| may occur. 
Information about dealing with this problem is given later in this section.
</Quote>

and sure enough later in the document they explain it. Basically prior 
to MySQL 5.0.12, Join and the comma operator were treated the same, but 
in 5.0.12 and later, the join keyword has higher precedence than the 
comma. So because the wanted pages code simplified is "... From 
link,page Join page join nonempty ..." MySQLl joins the link table last 
because it is joined by a comma rather than the join keyword.

The Solution:
in wiki/lib/WikiDB/backend/PearDB_mysql.php line 127:
Change
. " FROM $link_tbl,$page_tbl as linked "
To
. " FROM $link_tbl JOIN $page_tbl  as linked "

-William Leader