Suppose if we provide an empty string for padding on LPAD() or RPAD() functions then MySQL will return NULL as output. Following example will demonstrate it −
Example
mysql> Select LPAD('ABCD',22,''); +--------------------+ | LPAD('ABCD',22,'') | +--------------------+ | NULL | +--------------------+ 1 row in set (0.00 sec) mysql> Select RPAD('ABCD',22,''); +--------------------+ | RPAD('ABCD',22,'') | +--------------------+ | NULL | +--------------------+ 1 row in set (0.00 sec)