People face many connectivity issues while connecting to different SQL versions (MS SQL 2005,2008,2012). We shall be providing quick review of how to connect to different Versions on your local machine.
1- Connecting SQL 2005 :

ServerName: is Your computerName which can be found from your My Computer /This PC ‘s and \SQLEXPRESS .
2- Connecting SQL 2008 :

ServerName: is Your computerName which can be found from your My Computer /This PC ‘s and \SQLEXPRESS .
3- Connecting SQL 2012 :

ServerName: is Just Your ComputerName
