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(mysql.info)Using DATE

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Problems Using `DATE' Columns
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The format of a `DATE' value is `'YYYY-MM-DD''. According to ANSI SQL,
no other format is allowed. You should use this format in `UPDATE'
expressions and in the WHERE clause of `SELECT' statements.  For
example:

     mysql> SELECT * FROM tbl_name WHERE date >= '1997-05-05';

As a convenience, MySQL automatically converts a date to a number if
the date is used in a numeric context (and vice versa). It is also smart
enough to allow a "relaxed" string form when updating and in a `WHERE'
clause that compares a date to a `TIMESTAMP', `DATE', or a `DATETIME'
column.  (Relaxed form means that any punctuation character may be used
as the separator between parts. For example, `'1998-08-15'' and
`'1998#08#15'' are equivalent.) MySQL can also convert a string
containing no separators (such as `'19980815''), provided it makes
sense as a date.

The special date `'0000-00-00'' can be stored and retrieved as
`'0000-00-00'.' When using a `'0000-00-00'' date through *MyODBC*, it
will automatically be converted to `NULL' in *MyODBC* Version 2.50.12
and above, because ODBC can't handle this kind of date.

Because MySQL performs the conversions described above, the following
statements work:

     mysql> INSERT INTO tbl_name (idate) VALUES (19970505);
     mysql> INSERT INTO tbl_name (idate) VALUES ('19970505');
     mysql> INSERT INTO tbl_name (idate) VALUES ('97-05-05');
     mysql> INSERT INTO tbl_name (idate) VALUES ('1997.05.05');
     mysql> INSERT INTO tbl_name (idate) VALUES ('1997 05 05');
     mysql> INSERT INTO tbl_name (idate) VALUES ('0000-00-00');
     
     mysql> SELECT idate FROM tbl_name WHERE idate >= '1997-05-05';
     mysql> SELECT idate FROM tbl_name WHERE idate >= 19970505;
     mysql> SELECT mod(idate,100) FROM tbl_name WHERE idate >= 19970505;
     mysql> SELECT idate FROM tbl_name WHERE idate >= '19970505';

However, the following will not work:

     mysql> SELECT idate FROM tbl_name WHERE STRCMP(idate,'19970505')=0;

`STRCMP()' is a string function, so it converts `idate' to a string and
performs a string comparison.  It does not convert `'19970505'' to a
date and perform a date comparison.

Note that MySQL does no checking whether or not the date is correct.
If you store an incorrect date, such as `'1998-2-31'', the wrong date
will be stored. If the date cannot be converted to any reasonable
value, a `0' is stored in the `DATE' field.  This is mainly a speed
issue and we think it is up to the application to check the dates, and
not the server.