Combining two fields data into one field in the same database table

If you only want to display the name after combining the fields then simply use:
SELECT CONCAT(first_name, ‘ ‘, last_name) AS full_name FROM table_name;

But if you want to save them in a separate db field then use UPDATE query. To update all the records in the table in one shot use:

UPDATE table_name SET full_name = CONCAT(first_name, ‘ ‘, last_name);