i am trying to acess data base from my cusom web part

the piece of code for connection is working fine when i use it as
ASP web
application

but when i use the same in web part library template it is not
giving the
result

i made trust level as WSS_Medium

and in assembly info.cs i have added the following line

[assembly: AllowPartiallyTrustedCallers()]


i would like to know is there any other technique to be followed

can anyone please give the solution