year = 2 YY it's diff year from reference year say 2000. we can have 26+26+10 aphabets to combine ! months = 1 M a-l map each month to single alphabet days = 1 D a-z A-G hours = 1 H a-y (map a char to a-x) seconds: 1 60 a-z , A-Z 0-9 chars total 26+26+10 ==> 62 avaiable chars Keep all dates in GMT format for storing. It fits in 6 chars ! May be we can use 1 more char as year extention if needed. Obviously, we need have custom functions to convert timedate from normal to this format.