MySQL: NULL 0 qoj

#coalesce#done#mysql#null#sql

QujHom vaD MySQL column values vIqoj 'ej sum sort vIneH. misvam:

SELECT ITEMS.id, SUM(VOTES.modificator) AS score
FROM items ITEMS
LEFT JOIN votes VOTES ON ITEMS.id = VOTES.item
GROUP BY ITEMS.id
ORDER BY score DESC

'ach: Hu'! votes table Daq entry pagh DaH arithmetic function "null" nob. 'ach sum Dung sort DaneH. null value nuq? jIH Dochvam Daq 0. vaj null 0 choH:

SELECT ITEMS.id, COALESCE(SUM(VOTES.modificator), 0) AS score
FROM items ITEMS
LEFT JOIN votes VOTES ON ITEMS.id = VOTES.item
GROUP BY ITEMS.id
ORDER BY score DESC

COALESCE nuq Qu'? simple "convert" law'. COALESCE parameters law' ghaj 'ej wa'DIch value ghaj (null pagh) nob.

COALESCE(NULL, NULL, 'Hallo', NULL, 'Elefant')

"Hallo" nob.

jIH example Daq COALESCE sum VOTES.modificator nob, 'ach "value" null (null value pagh 'oH) vaj 0 nob 'ej arithmetic function result choH.