powershell - How best to change SQL passwords and update all the connection strings on a farm? -

i new powershell , wondering if possible accomplish following, based on requirement change sql passwords every 3 months , update websites web.config files have connections strings @ same time new sql password. ideally new sql passwords, server names & databases stored in file (sql table, xml files, csv, etc) , script reads in file. script changes sql passwords based on content of table contains names of servers , databases. after step 1, script updates web.configs connection strings in 20 websites new password used in step 1. guess need table hold path web.configs too. repeats process changing sql password , updating 20 websites. nice have creating backup copy of web.config prior modifying , wrapping script in transaction in case script encounters error.