式門遁甲

一般都是直接用某個Connection去建立連接
像是SqlConnection或是OleDbConnection..等等
但另外有個通用法，只要改Provider就可改連接的方法
這是在 System.Data.Common裡面的

DbProviderFactory theFactory =
 DbProviderFactories.GetFactory("System.Data.SqlClient");

ConnectionStringSettings theConnectionString =
    ConfigurationManager.ConnectionStrings["myConnectnioStr"];
   
DbConnection theConnection = theFactory.CreateConnection();

theConnection.Open();

if (theConnection.State == System.Data.ConnectionState.Open)
       returnMessage = "資料庫的連接已開";
}
catch (DbException dbexception)
{
       returnMessage = dbexception.Message;
}
catch (Exception exception)
{
      returnMessage = exception.Message;
}

另外補上theFactory可用的方法和屬性
方法
CreateCommand
CreateCommandBuilder
CreateConnection
CreateConnectionStringBuilder
CreateDataAdapter
CreateDataSourceEnumerator
CreateParameter
CreatePermission
屬性
CanCreateDataSourceEnumerator