What are the main differences between InnoDB and MyISAM

InnoDB has row-level locking, MyISAM can only do full table-level locking. 

InnoDB has better crash recovery. 

MyISAM has FULLTEXT search indexes, InnoDB did not until MySQL 5.6 (Feb 2013).

InnoDB implements transactions, for foreign  keys and relationship constraints, MyISAM does not

Default MySQL Storage Engine ?

Starting from MySQL 5.5.5, the default storage engine for new tables is InnoDB .

convert string into array

$str = "Hello Friend";
$arr1 = str_split($str);$arr2 = str_split($str, 3);
print_r($arr1);print_r($arr2);
?>

The above example will output:

Array
(
    [0] => H
    [1] => e
    [2] => l
    [3] => l
    [4] => o
    [5] =>
    [6] => F
    [7] => r
    [8] => i
    [9] => e
    [10] => n
    [11] => d
)

Array
(
    [0] => Hel
    [1] => lo
    [2] => Fri
    [3] => end
)