方法一.
如果在config文件中已经完成连接配置:
string connString = new DatabaseProviderFactory().CreateDatabase("你的Instance").GetConnection().ConnectionString;
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方法二.
string a,b,c,d;
DatabaseConfigurationView view = new DatabaseConfigurationView(ConfigurationManager.GetCurrentContext());
ConnectionStringData connectionStringData = view.GetDatabaseSettings().ConnectionStrings["你在配置文件中定义好的名字"];
a = connectionStringData.Parameters["database"].Value
b = connectionStringData.Parameters["Integrated Security"].Value
c = connectionStringData.Parameters["database"].Value
d = connectionStringData.Parameters["server"].Value
(其他的类似)
最后,把a,b,c,d连接起来。