mysql_group by 奇怪问题解决
我回去查了一下关于mysql group by 奇怪的现像，
可以通过修改sql_mode的方法改变这种奇怪的现像。
例如下：
mysql>SELECTjob,sal,deptno
->FROMemp
->GROUPbydeptno;
+----------+---------+--------+
|job|sal|deptno|
+----------+---------+--------+
|MANAGER|2450.00|10|
|CLERK|800.00|20|
|SALESMAN|1600.00|30|
+----------+---------+--------+
3rowsinset(0.04sec)
mysql>setsql_mode="STRICT_TRANS_TABLES,ONLY_FULL_GROUP_BY";
QueryOK,0rowsaffected(0.00sec)
mysql>SELECTjob,sal,deptno
->FROMemp
->GROUPbydeptno;
ERROR1055(42000):'tao.emp.JOB'isn'tinGROUPBY
mysql>SELECTcount(job),count(sal),deptno
->FROMemp
->GROUPBYdeptno;
+------------+------------+--------+
|count(job)|count(sal)|deptno|
+------------+------------+--------+
|3|3|10|
|5|5|20|
|6|6|30|
+------------+------------+--------+
3rowsinset(0.00sec)
//-------------------------------------------------
//以上修改sql_mode只在当前会话中生效.
//如果需要长期有效请修改my.ini文件中
#sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
sql_mode="STRICT_TRANS_TABLES,ONLY_FULL_GROUP_BY"