c# - Sql connection string for data access layer -

i using direct connection string is

string constring = "data source=.\\sqlexpress; initial catalog=mydb; integrated security=sspi";

i need connection string stored in web.config file like:

<connectionstrings> <add name="sqlcon" connectionstring="data source=.\\sqlexpress; initial catalog=mydb; integrated security=sspi" providername="system.data.sqlclient" /> </connectionstrings> 

the problem is not accessible in data access layer. working on 3 layer architecture model. won't adding references data access layer, such system.web etc. every day class libraries more , more classes. realize time use globally accessible connection string when submit project connection string need changed @ 1 place on university computer.

you won't have add reference web dlls in data access layer.

it depends on structure, if dlls copied web sites's bin folder thorough project references - web config connection string used directly web site's web config. connection resolved @ runtime in host web site hosted web server. no need add 1 data access dll itself. means single process architecture - connection string globally available.

if data access layer hosted on app server, might have web config web service exposing business/data layer. common pattern expose business layer w/data access using wcf service. service have it's own web.config file - separate web.config defined web site. key point though wfc service needs connection string. web site's web config typically contain information how invoke service (wcf configuration).