32-bit and 64-bit reshaping in PHP and MySQL is how many _php instances

One byte has 8 bits, so the 32-bit int occupies 32-bit/8-bit = 4-byte, and 64-bit int uses 64-bit/8-bit = 8 bytes.

32-bit, 64-bit unsigned integer maximum value:

2^64-1 = 18446744073709551615

2^32-1 = 4294967295

32-bit, 64-bit signed integer maximum value:

(2^32)/2-1 = 2147483647

(2^64)/2-1 = 9223372036854775807

Minus 1 is because the integer consists of 0.

The value of the 64-bit Ubuntu 14.04,php_int_max is 9223372036854775807, as is the maximum value of the signed bigint type in MySQL.

The value of the 32-bit Ubuntu 14.04,php_int_max is 2147483647, as is the maximum value for a signed INT in MySQL.

echo Date (' y-m-d h:i:s ', Php_int_max); Back 2038-01-19 11:14:07

echo strtotime (' 2038-01-19 11:14:07 '); Return 2147483647

echo strtotime (' 2038-01-19 11:14:08 '); 32-bit return null

That is, the maximum time () of PHP on a 32-bit system can only return the timestamp of the 2038-01-19 11:14:07.

Field type: ' Posted ' int (a) unsigned not NULL DEFAULT ' 0 '

32-bit MySQL (64-bit MySQL is also the case), inserting a larger number than the 32-bit unsigned int maximum 2^32-1 = 4294967295 will cause an error:

UPDATE ' punbb ' pb_topics ' SET ' posted ' = ' 4294967296 ' WHERE ' pb_topics '. ' id ' = 1;

Warning: #1264 out of range value for column ' posted ' at row 1

However, MySQL can store 64-bit integers with a 8-byte bigint type.

Data type	LP64	ILP64	LLP64	ILP32	LP32
Char	8	8	8	8	8
Short	16	16	16	16	16
_int32	N/A	32	N/A	N/A	N/A
Int	32	64	32	32	16
Long	64	64	32	32	32
Long Long	N/A	N/A	64	N/A	N/A
Pointer	64	64	64	32	32

The above content is a small series to introduce 32-bit and 64-bit plastic surgery range, I hope to help.