General error: 1364 Field city_id doesn't have a default value

I have upgraded the MySQL from 5.5 to 5.6 and then getting below type of errors.
General error: 1364 Field 'city_id' doesn't have a default value

(I was not getting such type of error, it must come after upgrading my MySQL Version from 5.5 to 5.6)

Solution: It have 3 Solutions

1. In Your Code (PHP), always set a default value (if no value) before save.
   

   $objSaveData->saveData(
       array(
           'id'=>111,
           'name'=>'New user',
           'city_id'=>0, //default value
       );
   );
   

2. Create fields with default values set in datatable. It could be empty string, which is fine for MySQL server running in strict mode.
   like below:

   ALTER TABLE `users` CHANGE `city_id` `city_id` INT(10) UNSIGNED NOT NULL DEFAULT '0';
   

3. Disable MySQL Strict Mode (Most appropriate)
   Disable it by setting your own SQL_MODE in the my.cnf file, then restart MySQL.
   
   Look for the following line:
   

   sql-mode = "STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"

   Change it to:

   sql-mode="" 

   Restart the MySQL Service.