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11.3.4. Y2K Issues and Date Types

As discussed in Section 1.4.5, “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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