(mysql.info) y2k-issues

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(mysql.info) year

(mysql.info) date-and-time-types

 
 11.3.4 Y2K Issues and Date Types
 --------------------------------
 
 As discussed in  year-2000-compliance, MySQL itself is year 2000
 (Y2K) safe. However, particular input values presented to MySQL may not
 be Y2K safe. Any value containing a two-digit year is ambiguous,
 because the century is unknown.  Such values must be interpreted into
 four-digit form because MySQL stores years internally using four digits.
 
 For `DATETIME', `DATE', `TIMESTAMP', and `YEAR' types, MySQL interprets
 dates with ambiguous year values using the following rules:
 
    * Year values in the range `00-69' are converted to `2000-2069'.
 
    * Year values in the range `70-99' are converted to `1970-1999'.
 
 Remember that these rules are only heuristics that provide reasonable
 guesses as to what your data values mean. If the rules used by MySQL do
 not produce the correct values, you should provide unambiguous input
 containing four-digit year values.
 
 `ORDER BY' properly sorts `YEAR' values that have two-digit years.
 
 Some functions like `MIN()' and `MAX()' convert a `YEAR' to a number.
 This means that a value with a two-digit year does not work properly
 with these functions. The fix in this case is to convert the
 `TIMESTAMP' or `YEAR' to four-digit year format.
 

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(mysql.info) year

(mysql.info) date-and-time-types