给看看下面两个都能防什么？怎么使用？
function ForSqlForm()
dim fqys,errc,i,items
dim nothis(18) 
nothis(0)="net user" 
nothis(1)="xp_cmdshell" 
nothis(2)="/add" 
nothis(3)="exec%20master.dbo.xp_cmdshell" 
nothis(4)="net localgroup administrators" 
nothis(5)="select" 
nothis(6)="count" 
nothis(7)="asc" 
nothis(8)="char" 
nothis(9)="mid" 
nothis(10)="''" 
nothis(11)=":" 
nothis(12)="""" 
nothis(13)="insert" 
nothis(14)="delete" 
nothis(15)="drop" 
nothis(16)="truncate" 
nothis(17)="from" 
nothis(18)="%"
nothis(19)="@"  
errc=false 
for i= 0 to ubound(nothis) 
  for each items in request.Form
  if instr(request.Form(items),nothis(i))<>0 then 
   response.write("<div>")
   response.write("你所填写的信息:" & server.HTMLEncode(request.Form(items)) & "<br>含非法字符:" & nothis(i))
   response.write("</div>")
   response.write("对不起,你所填写的信息含非法字符！<a href=""#"" onclick=""history.back()"">返回</a>")
   response.End()
  end if 
  next
next 
end function


function ForSqlInjection()
dim fqys,errc,i
dim nothis(19) 
fqys = request.ServerVariables("QUERY_STRING")
nothis(0)="net user" 
nothis(1)="xp_cmdshell" 
nothis(2)="/add" 
nothis(3)="exec%20master.dbo.xp_cmdshell" 
nothis(4)="net localgroup administrators" 
nothis(5)="select" 
nothis(6)="count" 
nothis(7)="asc" 
nothis(8)="char" 
nothis(9)="mid" 
nothis(10)="''" 
nothis(11)=":" 
nothis(12)="""" 
nothis(13)="insert" 
nothis(14)="delete" 
nothis(15)="drop" 
nothis(16)="truncate" 
nothis(17)="from" 
nothis(18)="%"
nothis(19)="@"  
errc=false 
for i= 0 to ubound(nothis) 
if instr(FQYs,nothis(i))<>0 then 
errc=true 
end if 
next 
if errc then 
response.write "查询信息含非法字符！<a href=""#"" onclick=""history.back()"">返回</a>" 
response.end 
end if 
end function