c# - How to connection string in web.config from databases names in dropdown -
i have dropdown has list of databases. user has select database has use , gridview shown. so display gridview i'm giving below connection string in code behind file. using (sqlconnection con = new sqlconnection(@"data source=hki-d-sql05\sql2k12;initial catalog=" + dropdownlist1.selectedvalue + ";user id=sa;password=sa123")) but there anyways list connection string in web.congfig file? database name has selected in code behind. means server name, user id , password can given in web config initial catalog in code behind. you can use placeholder database name in web.config (e.g. " data source=hki-d-sql05\sql2k12;initial catalog={{placeholder}};user id=sa;password=sa123 "). in code behind connection string value web.config , replace placeholder selected database (using .replace("{{placeholder}}", dropdownlist1.selectedvalue) ).