MySQL Server itself has no problems with Year 2000 (Y2K) compliance:
MySQL Server uses Unix time functions that handle dates into the year
2038
forTIMESTAMP
values. ForDATE
andDATETIME
values, dates through the year9999
are accepted.All MySQL date functions are implemented in one source file,
sql/time.cc
, and are coded very carefully to be year 2000-safe.In MySQL, the
YEAR
data type can store the years0
and1901
to2155
in one byte and display them using two or four digits. All two-digit years are considered to be in the range1970
to2069
, which means that if you store01
in aYEAR
column, MySQL Server treats it as2001
.
Although MySQL Server itself is Y2K-safe, you may run into
problems if you use it with applications that are not Y2K-safe.
For example, many old applications store or manipulate years
using two-digit values (which are ambiguous) rather than
four-digit values. This problem may be compounded by
applications that use values such as 00
or
99
as “missing” value
indicators. Unfortunately, these problems may be difficult to
fix because different applications may be written by different
programmers, each of whom may use a different set of conventions
and date-handling functions.
Thus, even though MySQL Server has no Y2K problems, it is the application's responsibility to provide unambiguous input. 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 to2000-2069
.Year values in the range
70-99
are converted to1970-1999
.
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.