Moodle in English

Hi all. Sorry if this looks like a newbie problem, because I am a newbie to Moodle and SQL in general. I saw this contributed SQL report written in some SQL DBMS. Now I learned that our Moodle installation uses postgresql and this code doesn't work.

SELECT 
l.id, 
l.timecreated, 
DATE_FORMAT(FROM_UNIXTIME(l.timecreated),'%d-%m-%Y') AS dTime,
@prevtime := (SELECT MAX(timecreated) FROM mdl_logstore_standard_log 
		WHERE userid = %%USERID%% AND id < l.id ORDER BY id ASC LIMIT 1) AS prev_time,
IF (l.timecreated - @prevtime < 7200, @delta := @delta + (l.timecreated-@prevtime),0) AS sumtime,
l.timecreated-@prevtime AS delta,
"User" AS TYPE

FROM prefix_logstore_standard_log AS l, 
(SELECT @delta := 0) AS s_init 
 # CHANGE UserID
WHERE l.userid = %%USERID%% AND l.courseid = %%COURSEID%%
%%FILTER_STARTTIME:l.timecreated:>%% %%FILTER_ENDTIME:l.timecreated:<%%

I would appreciate it if somebody can guide me through re-writing this in postgresql. Thanks in advance!