[TYPO3] debug queries

[Andrea Giorgini]

Hi all,
how do I debug queries with typo3? I'm watching my mysql.log file with a 
grep on the name of the table but cannot see anything...
In particular, was trying to put a limit:

$res = 
$GLOBALS['TYPO3_DB']->exec_SELECTquery('*','table_name',"deleted=0","","","limit 
0,1");


but there must be an error...

Thanks a lot
Andrea