zkuste použít TIMEDIFF( ) a poddotaz
SELECT TIMEDIFF((SELECT `entered_at` FROM `demo_test3` WHERE `id`='1'),
(SELECT `entered_at` FROM `demo_test3` WHERE `id`='3'))
zkuste použít TIMEDIFF( ) a poddotaz
SELECT TIMEDIFF((SELECT `entered_at` FROM `demo_test3` WHERE `id`='1'),
(SELECT `entered_at` FROM `demo_test3` WHERE `id`='3'))