PHP and ODBC
While looking for something else in the Moodle Forums, I found these links that refer to the underlying way Moodle connects to databases using ODBC.
“adodb just harnesses the underlying PHP functions for whatever type of connection you use, so it helps to be familiar with how they work.”
(Links taken from this Moodle Forums post. http://moodle.org/mod/forum/discuss.php?d=74133)
Please add more, if you find any.