ASP代码问题,请问这段代码什么意思?

<%
if request("action")="loginout" then
session.abandon
Response.Redirect ("index.asp")
end if

if request("login")="check" then
if request("admin")=admin and md5(request("password"))=password then
session("login")="ok"
response.write "<script language='javascript'>"
response.write "alert('欢迎登入！管理结束后请记得点击“退出管理”！');"
response.write "location.href='book_admin.asp';"
response.write "</script>"
else
response.write "<script language='javascript'>"
response.write "alert('管理员用户名称或密码输入有误，请检查后重新输入！');"
response.write "location.href='javascript:history.go(-1)';"
response.write "</script>"
response.end
end if
end if

function lleft(cont

<%
if request("action")="loginout" then ' 通过request 对象。得到action的值 ，如果值是loginout 则 把session所以对象晴空
session.abandon '
Response.Redirect ("index.asp") '返回到index.asp 页
end if

if request("login")="check" then ' 判断 login的值 是否等于 check
if request("admin")=admin and md5(request("password"))=password then '判断用户密码是否正确 ，怎么没有有打开数据表的代码？
session("login")="ok"
response.write "<script language='javascript'>"
response.write "alert('欢迎登入！管理结束后请记得点击“退出管理”！');"
response.write "location.href='book_admin.asp';"
response.write "</script>"
else
response.write "<script language='javascript'>"
response.write "alert('管理员用户名称或密码输入有误，请检查后重新输入！');"