Upgrade MySQL 5.5 to 5.6 -- Ubuntu 14.04

Step 1 : Take a backup:

 mysqldump --lock-all-tables -u root -p --all-databases > dump.sql  

Step 2 : Remove your older version of  MySQL:

 sudo apt-get remove mysql-server  

 sudo apt-get autoremove  

Step 3 : Install new version of MySQL:

 sudo apt-get install mysql-client-5.6 mysql-client-core-5.6  

 sudo apt-get install mysql-server-5.6  

Step 4 : Restore your data:

 mysql -u root -p < dump.sql