怎么会这么怪的呢？

[glcity]

现有一数据表"glcity_pl"中定义一字段"pl_dt"成datetime类型,
该数据表中有一条记录存在，其中字段"pl_dt"的值为“2008-4-10 9:54:30”，
但做如下的查询，怎么会查不出这条记录呢？

select * from glcity_pl where (pl_dt - 2008-04-08) >= 0 and (pl_dt - 2008-04-16) <= 0

如果“select * from glcity_pl where (pl_dt - 2008-04-08) >= 0”这样查就可把这条记录查出来！
请问我的错误在哪呀？先谢谢了！

或者要怎么才能查出来？

[zanyzyg]

加'2008-04-08'

或者用datediff
或者用between

[zanyzyg]

select * from glcity_pl where (pl_dt - '2008-04-08') >= 0 and (pl_dt - '2008-04-16') <= 0

[wgzaaa]

去学下数据类型吧

[glcity]

谢谢各位帮忙！！！

[sweetweiwei]

改为select * from glcity_pl where (pl_dt - 2008-04-08) >= 0 and (pl_dt - 2008-04-16) >= 0
或者select * from b where datediff(dd,convert(char(10),pl_dt,120) , '2008-04-08') <= 0
and datediff(dd,convert(char(10),pl_dt,120), '2008-04-16') >= 0

[glcity]

我这样做
select * from glcity_pl where DATEDIFF(day,pl_dt,2008-04-08) <= 0 and DATEDIFF(day,2008-04-16,pl_dt) >= 0

已解决了！
多谢zanyzyg及wgzaaa朋友的帮忙！

[glcity]

我这句语句还是有问题的，
select * from glcity_pl where DATEDIFF(day,pl_dt,2008-04-08) <= 0 and DATEDIFF(day,pl_dt,2008-04-16) <= 0

我们来看看语法：
DATEDIFF ( datepart , startdate , enddate )
startdate 是从 enddate 减去。如果 startdate 比 enddate 晚，返回负值。

pl_dt=“2008-4-10 9:54:30”
请看第一个查询条件“2008-4-10”比“2008-04-08”晚吧，返回负值，对的。
请看第二个查询条件“2008-4-10”比“2008-04-16”晚吗？
为什么还是返回负值呢？