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1.4.5. Year 2000 Compliance

The MySQL Server itself has no problems with Year 2000 (Y2K) compliance:

  • MySQL Server uses Unix time functions that handle dates into the year 2037 for TIMESTAMP values. For DATE and DATETIME values, dates through the year 9999 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 years 0 and 1901 to 2155 in one byte and display them using two or four digits. All two-digit years are considered to be in the range 1970 to 2069, which means that if you store 01 in a YEAR column, MySQL Server treats it as 2001.

The following simple demonstration illustrates that MySQL Server has no problems with DATE or DATETIME values through the year 9999, and no problems with TIMESTAMP values until after the year 2030:

mysql> DROP TABLE IF EXISTS y2k;
Query OK, 0 rows affected (0.00 sec)

mysql> CREATE TABLE y2k (date DATE,
    ->                   date_time DATETIME,
    ->                   time_stamp TIMESTAMP);
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO y2k VALUES
    -> ('1998-12-31','1998-12-31 23:59:59','1998-12-31 23:59:59'),
    -> ('1999-01-01','1999-01-01 00:00:00','1999-01-01 00:00:00'),
    -> ('1999-09-09','1999-09-09 23:59:59','1999-09-09 23:59:59'),
    -> ('2000-01-01','2000-01-01 00:00:00','2000-01-01 00:00:00'),
    -> ('2000-02-28','2000-02-28 00:00:00','2000-02-28 00:00:00'),
    -> ('2000-02-29','2000-02-29 00:00:00','2000-02-29 00:00:00'),
    -> ('2000-03-01','2000-03-01 00:00:00','2000-03-01 00:00:00'),
    -> ('2000-12-31','2000-12-31 23:59:59','2000-12-31 23:59:59'),
    -> ('2001-01-01','2001-01-01 00:00:00','2001-01-01 00:00:00'),
    -> ('2004-12-31','2004-12-31 23:59:59','2004-12-31 23:59:59'),
    -> ('2005-01-01','2005-01-01 00:00:00','2005-01-01 00:00:00'),
    -> ('2030-01-01','2030-01-01 00:00:00','2030-01-01 00:00:00'),
    -> ('2040-01-01','2040-01-01 00:00:00','2040-01-01 00:00:00'),
    -> ('9999-12-31','9999-12-31 23:59:59','9999-12-31 23:59:59');
Query OK, 14 rows affected, 2 warnings (0.00 sec)
Records: 14  Duplicates: 0  Warnings: 2

mysql> SELECT * FROM y2k;
+------------+---------------------+---------------------+
| date       | date_time           | time_stamp          |
+------------+---------------------+---------------------+
| 1998-12-31 | 1998-12-31 23:59:59 | 1998-12-31 23:59:59 |
| 1999-01-01 | 1999-01-01 00:00:00 | 1999-01-01 00:00:00 |
| 1999-09-09 | 1999-09-09 23:59:59 | 1999-09-09 23:59:59 |
| 2000-01-01 | 2000-01-01 00:00:00 | 2000-01-01 00:00:00 |
| 2000-02-28 | 2000-02-28 00:00:00 | 2000-02-28 00:00:00 |
| 2000-02-29 | 2000-02-29 00:00:00 | 2000-02-29 00:00:00 |
| 2000-03-01 | 2000-03-01 00:00:00 | 2000-03-01 00:00:00 |
| 2000-12-31 | 2000-12-31 23:59:59 | 2000-12-31 23:59:59 |
| 2001-01-01 | 2001-01-01 00:00:00 | 2001-01-01 00:00:00 |
| 2004-12-31 | 2004-12-31 23:59:59 | 2004-12-31 23:59:59 |
| 2005-01-01 | 2005-01-01 00:00:00 | 2005-01-01 00:00:00 |
| 2030-01-01 | 2030-01-01 00:00:00 | 2030-01-01 00:00:00 |
| 2040-01-01 | 2040-01-01 00:00:00 | 0000-00-00 00:00:00 |
| 9999-12-31 | 9999-12-31 23:59:59 | 0000-00-00 00:00:00 |
+------------+---------------------+---------------------+
14 rows in set (0.00 sec)

The final two TIMESTAMP column values are zero because the year values (2040, 9999) exceed the TIMESTAMP maximum. The TIMESTAMP data type, which is used to store the current time, supports values that range from '1970-01-01 00:00:00' to '2030-01-01 00:00:00' on 32-bit machines (signed value). On 64-bit machines, TIMESTAMP handles values up to 2106 (unsigned value).

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. See Section 11.3.4, “Y2K Issues and Date Types”, for MySQL Server's rules for dealing with ambiguous date input data that contains two-digit year values.


 
 
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