Timestamps are a preferential format to the memory of date and time with inputs in web pages which SQL data banks and PHP use. , Besides, the second value is covered of the Unix-Timestamp on 1st of January, 1970, 1:00:00 a.m. o'clock (CET). Timestamps do not become in the direct data time format  tt.mm.jjjj hh:mm:ss   ( dd.mm.yyyy - hh:mm:ss ) uses , but in the second time format - the number (sum) of the past seconds since the just called date. Preferential operational areas are web pages like visitors' books, data input lists, data banks etc. which file the data in the SQL data bank (MySQL) - in the case beside other information also input date a. input time .
With it one is in of the situation to change entry date as well as entry time (e.g., with comments to visitors' book entries by the web master or Admin of the HP) or maintained if these can originate from transference, Back the backups - or by complete additional comment contribution changes.
In this case after finished work simply click the 'convert'-button - ready.  The present Timestamp goes at most up to the 19th of January, 2038 - 04:14:07 a.m. o'clock (max. Timestamp = 2147483647) - investigates on the 05th of November, 2012.