Hoe tijd te krijgen van db, afhankelijk van de omstandigheden?

Gebruik de timestampdiff functie daarvoor en CASE :

select case 
        when TIMESTAMPDIFF(SECOND, `date`,current_timestamp) <= 60 
        then concat(TIMESTAMPDIFF(SECOND, `date`,current_timestamp), ' seconds')
        when TIMESTAMPDIFF(DAY, `date`,current_timestamp) <= 3 
        and TIMESTAMPDIFF(DAY, `date`,current_timestamp) >= 1 
        ...
       end as time_diff 
from Table_hello
where TIMESTAMPDIFF(DAY, `time`,current_timestamp) >= 3