MySQL COALESCE() function returns the blank if it has a blank as the first argument. It is because blank is also a non-NULL value and we know that COALESCE function always returns first non-NULL value as a result. Following example would demonstrate it −
Example
mysql> Select COALESCE('','Ram'); +--------------------+ | COALESCE('','Ram') | +--------------------+ | | +--------------------+ 1 row in set (0.00 sec)