데이터베이스 설계

data type

 

1byte = 8 bit

 

MAX LENGTH for each data type IN DB

(~characters long)

UUID 36

universally unique identifier

128-bit number = 16 octets(bytes *nowadays 1byte doesn't always mean 8bit)

form 8-4-4-4-12 for a total of 36 characters (32 hexadecimal characters and 4 hyphens)

ex) a81bc81b-dead-4e5d-abff-90865d1e13b1

 

If the UUID value is the primary key, the canonical 36-byte string is converted to a 19-byte string, then is saved on disk. If the UUID value is a non-primary key, the canonical 36-byte string is converted to a 16-byte array, then is saved on disk.

 

canonical textual representation of a UUID: 

xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

SSID 32

 

 

IPV4 15

ex) 192.168.0.0 => 3*4+3=15

MAC 17

기기에 부여되는 16진수 12자리 단말 식별 번호

12:34:56:78:90:AB

ex) 2*6+5=>17