SpirirHost Support Centre: MySQL Reference Manual p.395

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Table of Contents
1. General Information
2. MySQL Installation
3. Tutorial Introduction
4. Database Administration
5. MySQL Optimisation
6. MySQL Language Reference
7. MySQL Table Types
8. MySQL APIs
9. Extending MySQL

Chapter 6: MySQL Language Reference 395 YEAR 0000 The \zero" values are special, but you can store or refer to them explicitly using the values shown in the table. You can also do this using the values '0' or 0, which are easier to write. \Zero" date or time values used through MyODBC are converted automatically to NULL in MyODBC Version 2.50.12 and above, because ODBC can't handle such values. 6.2.2.1 Y2K Issues and Date Types MySQL itself is Y2K-safe (see Section 1.2.5 [Year 2000 compliance], page 9), but input values presented to MySQL may not be. Any input containing 2-digit year values is ambiguous, because the century is unknown. Such values must be interpreted into 4-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 provide only reasonable guesses as to what your data mean. If the heuristics used by MySQL don't produce the correct values, you should provide unambiguous input containing 4-digit year values. ORDER BY will sort 2-digit YEAR/DATE/DATETIME types properly. Note also that some functions like MIN() and MAX() will convert a TIMESTAMP/DATE to a number. This means that a timestamp with a 2-digit year will not work properly with these functions. The x in this case is to convert the TIMESTAMP/DATE to 4-digit year format or use something like MIN(DATE_ADD(timestamp,INTERVAL 0 DAYS)). 6.2.2.2 The DATETIME, DATE, and TIMESTAMP Types The DATETIME, DATE, and TIMESTAMP types are related. This section describes their char- acteristics, how they are similar, and how they dier. The DATETIME type is used when you need values that contain both date and time infor- mation. MySQL retrieves and displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' for- mat. The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'. (\Sup- ported" means that although earlier values might work, there is no guarantee that they will.) The DATE type is used when you need only a date value, without a time part. MySQL retrieves and displays DATE values in 'YYYY-MM-DD' format. The supported range is '1000- 01-01' to '9999-12-31'. The TIMESTAMP column type provides a type that you can use to automatically mark INSERT or UPDATE operations with the current date and time. If you have multiple TIMESTAMP columns, only the rst one is updated automatically. Automatic updating of the rst TIMESTAMP column occurs under any of the following con- ditions:

MySQL Reference Manual

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