for hungarian competitors:
<connectionStrings>
<remove name="LocalSqlServer"/>
<add name="LocalSqlServer" connectionString="Data source=.;AttachDbFileName=|DataDirectory|\ASPNETDB.mdf;Integrated Security=true;user instance=true" providerName="System.Data.SqlClient" />
</connectionStrings>
if you use aspnet membership provider you have to write the following lines into the web.config
for other countries the date source name is ./sqlexpress but the process is the same