oracle日期时间范围查询

SELECT * FROM testdatetime t WHERE 1=1 AND t.createdate >= ‘2011-06-01‘ AND t.createdate <= ‘2011-07-05‘;

SELECT * FROM testdatetime t WHERE 1=1 AND to_date(t.createdate,‘yyyy-MM-dd‘) 
between to_date(‘2011-06-01‘,‘yyyy-MM-dd‘) and to_date(‘20110705‘,‘yyyymmdd‘) ; 

SELECT * FROM testdatetime t WHERE 1=1 AND t.usedate >= ‘2011-06-01‘ AND t.usedate <= ‘2011-07-05‘;  
  
SELECT * FROM testdatetime t WHERE 1=1 AND to_date(t.usedate,‘yyyy-MM-dd HH24:MI:SS‘)
between to_date(‘2011-07-01 12:00:00‘,‘yyyy-MM-dd HH24:MI:SS‘) and to_date(‘20110702 12:00:00‘,‘yyyymmdd HH24:MI:SS‘) ;  

SELECT * FROM testdatetime t WHERE 1=1 AND t.startdate >= to_date(‘2011-07-01‘,‘yyyy-MM-dd‘) AND t.startdate <= to_date(‘2011-07-02‘,‘yyyy-MM-dd‘);  
SELECT * FROM testdatetime t WHERE 1=1 AND t.startdate between to_date(‘2011-07-01‘,‘yyyy-MM-dd‘) AND to_date(‘2011-07-02‘,‘yyyy-MM-dd‘); 
SELECT * FROM testdatetime t WHERE 1=1 AND t.startdate = to_date(‘2011-07-01 12:00:00‘,‘yyyy-MM-dd HH24:MI:SS‘); 
SELECT * FROM testdatetime t WHERE 1=1 AND to_char(t.startdate,‘yyyy-MM-dd‘) = ‘2011-07-01‘;
SELECT * FROM testdatetime t WHERE 1=1 AND to_char(t.startdate,‘yyyy-MM-dd‘) >= ‘2011-07-01‘ AND to_char(t.startdate,‘yyyy-MM-dd‘) <= ‘2011-07-02‘;