asp查询代码问题

sql="select * from t_main where id in (select id from u_user where show=false)"
if request("type")<>"0" and request("type")<>"" then sql=sql+" and t_type='"&request("type")&"'"
if request("area")<>"0" and request("area")<>"" then sql=sql+" and t_area='"&request("area")&"'"
if request("job")<>"0" and request("job")<>"" then sql=sql+" and t_job='"&request("job")&"'"
if Trim(request("what"))<>"" then sql=sql+"and t_tit like '%"&Trim(request("what"))&"%'"
if request("date")<>"不限" and request("date")<>"" then sql=sql+" and datediff(t_time,Now())<"&request("date")
sql=sql+" order by t_time desc"
set rs=server.createobject("adodb.recordset")

Microsoft JET Database Engine '80004005'

表达式中的类型不匹配。

\wwwroot\wwwroot\search.asp, line 13