drop table if exists t1;set sql_mode="MySQL40";select @@sql_mode;@@sql_modeMYSQL40,HIGH_NOT_PRECEDENCEset @@sql_mode="ANSI";select @@sql_mode;@@sql_modeREAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,ANSISELECT 'A' || 'B';'A' || 'B'ABCREATE TABLE t1 (id INT, id2 int);SELECT id,NULL,1,1.1,'a' FROM t1 GROUP BY id;id	NULL	1	1.1	aSELECT id FROM t1 GROUP BY id2;iddrop table t1;SET @@SQL_MODE="";CREATE TABLE t1 (i int auto_increment NOT NULL, PRIMARY KEY (i));SHOW CREATE TABLE t1;Table	Create Tablet1	CREATE TABLE `t1` (  `i` int(11) NOT NULL auto_increment,  PRIMARY KEY  (`i`)) ENGINE=MyISAM DEFAULT CHARSET=latin1SET @@SQL_MODE="MYSQL323";SHOW CREATE TABLE t1;Table	Create Tablet1	CREATE TABLE `t1` (  `i` int(11) NOT NULL auto_increment,  PRIMARY KEY  (`i`)) TYPE=MyISAMSET @@SQL_MODE="MYSQL40";SHOW CREATE TABLE t1;Table	Create Tablet1	CREATE TABLE `t1` (  `i` int(11) NOT NULL auto_increment,  PRIMARY KEY  (`i`)) TYPE=MyISAMSET @@SQL_MODE="NO_FIELD_OPTIONS";SHOW CREATE TABLE t1;Table	Create Tablet1	CREATE TABLE `t1` (  `i` int(11) NOT NULL,  PRIMARY KEY  (`i`)) ENGINE=MyISAM DEFAULT CHARSET=latin1DROP TABLE t1;