如何判断输入的内容在数据库中是否存在？

我做了管理员登录输入用户名和密码。但是在登录验证的时候总是查找不到，可实际有这个用户名和密码：代码：``` @LANGUAGE="VBSCRIPT" CODEPAGE="936"

Response.Buffer=true

1<!-- #include file="conn.inc"-->

if (request.Form("username")="") or (Request.Form("password")="") then
redirectpage("manage.asp")
end if
if (request.Form("username")<>"") and (Request.Form("password")<>"") then
user=request.Form("username")
pas=request.Form("password")在这里可以得到user和pas的值
set rs=Conn.execute("select * from user where username="&user&" and password="&pas)
查找以后得不到
if rs("username")<>request.Form("username") then
response.Write("

1&lt;div align="center"&gt;用户名不存在，请重新输入&lt;/div&gt;

")
response.Write("

1&lt;div align="center"&gt;&lt;a href="javascript:history.back(1)"&gt;返回&lt;/a&gt;&lt;/div&gt;

")
end if
if rs("username")=request.Form("username") then
redirectpage("add.asp")
end if
end if

管理登录界面

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set rs=Conn.execute("select * from user where username='"&user&"' and password='"&pas&"'")

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set rs=Conn.execute("select * from user where username="&user&" and password="&pas)

==>

set rs=Conn.execute("select * from user where username='"&user&"' and password='"&pas&"'")
---------------------------------------------------------------

select ...
rs.open...
if rs.eof then
response.write "没有"
end if
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"select * from user where username="&user&" and password="&pas)
必须改为
("select * from user where username='"&user&"' and password='"&pas&"'")因为是字符形的

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把空格去掉

if rs("username")<>request.Form("username") then

==>

if trim(rs("username"))<>trim(request.Form("username")) then

用户名
	密码