Correct errors after migrate php version: Deprecated: mysql_pconnect(), charset, and Notice: Use of undefined constant No - assumed 'No' in...

Correct errors after migrate php version: 1- Deprecated: Deprecated: mysql_pconnect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in [...] 2- Charset: some files i changed to utf8 to correct but perhaps exists a general solution. Now shows charatcters as: "an�lisis" 3- And other text that appears on backend: Notice: Use of undefined constant No - assumed 'No' in [...]