发现SQL Server惊天大秘密！！

--set statistics xml on
CREATE TABLE T_TEST(ID INT IDENTITY PRIMARY KEY,CreateTime DATE)
INSERT INTO T_TEST SELECT '2011-11-04'
UNION ALL SELECT '2011-11-04'
UNION ALL SELECT '2011-11-04'
UNION ALL SELECT '2011-11-05'
UNION ALL SELECT '2011-11-05'
UNION ALL SELECT '2011-11-05'

SELECT * FROM T_TEST

SELECT COUNT(*) FROM T_TEST 
WHERE CreateTime>='2011-11-04 00:00:00' AND CreateTime <='2011-11-04 23:59:59'
--等价于(返回3行，这个没有问题)
SELECT COUNT(*) FROM T_TEST 
WHERE CreateTime='2011-11-04'


SELECT COUNT(*) FROM T_TEST 
WHERE CreateTime>='2011-11-04 00:00:00' AND CreateTime <'2011-11-04 23:59:59'
--等价于(返回0行，因为where条件无意义，这个也没有问题)
SELECT COUNT(*) FROM T_TEST 
WHERE CreateTime>='2011-11-04' AND CreateTime <'2011-11-04'


--传入参数为datetime类型(它为什么能返回3行？!!!!这是为什么！！)
SP_executesql N'
    select COUNT(*) 
    from T_TEST
    where CreateTime>=@BeginTime and CreateTime<@EndTime
',N'@BeginTime datetime,@EndTime datetime',
@BeginTime='2011-11-04 00:00:00',
@EndTime='2011-11-04 23:59:59'    

--修改了传参类型为date类型(返回0行)
SP_executesql N'
    select COUNT(*) 
    from T_TEST
    where CreateTime>=@BeginTime and CreateTime<@EndTime
',N'@BeginTime date,@EndTime date',
@BeginTime='2011-11-04 00:00:00',
@EndTime='2011-11-04 23:59:59'