After the installation of a CMS on XAMPP local host, I encountered a problem with MySQL which does not appear in installations on other hosts using other versions of MySQL.
After some investigations it was found that in the statement:
SELECT ..... FROM (t1,t2) LEFT JOIN t3 ON t3.a=t1.a WHERE ....
the parenthesis are mandatory, where other versions of MySQL are clearly more tolerant and do not require the parenthesis in this statement.