今天帮同事处理一个SQL(简化过后的)执行报错:
mysql> select date_format('2013-11-19','Y-m-d') > timediff('2013-11-19', '2013-11-20');ERROR 1267 (HY000): Illegal mix of collations (utf8_general_ci,COERCIBLE) and (latin1_swedish_ci,NUMERIC) for operation '>'
The language used for day and month names and abbreviations is controlled by the value of the lc_time_names system variable (Section 9.7, “MySQL Server Locale Support”).The DATE_FORMAT() returns a string with a character set and collation given by character_set_connection and collation_connection so that it can return month and weekday names containing non-ASCII characters.
mysql> set names utf8; mysql> select charset(date_format('2013-11-19','Y-m-d')), charset(timediff('2013-11-19', '2013-11-20')); +--------------------------------------------+-----------------------------------------------+ | charset(date_format('2013-11-19','Y-m-d')) | charset(timediff('2013-11-19', '2013-11-20')) | +--------------------------------------------+-----------------------------------------------+ | utf8 | binary | +--------------------------------------------+-----------------------------------------------+mysql> set names gb2312; mysql> select charset(date_format('2013-11-19','Y-m-d')), charset(timediff('2013-11-19', '2013-11-20')); +--------------------------------------------+-----------------------------------------------+ | charset(date_format('2013-11-19','Y-m-d')) | charset(timediff('2013-11-19', '2013-11-20')) | +--------------------------------------------+-----------------------------------------------+ | gb2312 | binary | +--------------------------------------------+-----------------------------------------------+
mysql> select date_format('2013-11-19','Y-m-d') > convert(timediff('2013-11-19', '2013-11-20') using utf8); +----------------------------------------------------------------------------------------------+ | date_format('2013-11-19','Y-m-d') > convert(timediff('2013-11-19', '2013-11-20') using utf8) | +----------------------------------------------------------------------------------------------+ | 1 | +----------------------------------------------------------------------------------------------+
P.S,MySQL的版本:5.5.20-55-log Percona Server (GPL), Release rel24.1, Revision 217