在MySQL中，考虑以下表： EMP（empId empName empSalary empJoinDate）， 要找出EMP表中empJoinDate在2012-10-01和2012-12-30之间的记录数，哪条SQL不正确？( )
Select count(*) from EMP where empJoinDate between '2012-10-01' and 2012-12-30';
Select count(1) from EMP where empJoinDate between '2012-10-01' and 2012-12-30';
Select count(*) from EMP where empJoinDate between '2012-10-01' and 2012-12-30' group by EXTRACT(YEAR_MONTH from empJoinDate );
Select sum(1) from EMP where empJoinDate >="2012-10-01" and empJoinDate <="2012-12-30";
都不是
