select * from client_info where month(CREATED_DT) =

month('2013-9-01') and year(CREATED_DT) = year('2013-09-01');

datediff;
在mysql 中 select datediff('2003-01-01','2003-01-02');
在SQL   中 select datediff(hh,'2003-01-01','2003-01-02');