Si pones en el web.config, en la secciion de configuration:
<connectionStrings>
<add name="xxxxMICONEIXON" connectionString="Data Source=NOMBRE_DE TU _SERVIDOR\SQLEXPRESS;Initial Catalog=TU_DATABASE;Integrated Security=True;MultipleActiveResultSets=False;Packe t Size=4096;Application Name="Microsoft SQL Server Management Studio Express""
providerName="System.Data.SqlClient" />
</connectionStrings>