mise à jour une colonne avec des données avg d'une autre colonne de table

Question

je l'ai écrit une commande comme celui-ci de mettre à jour une colonne dans une table avec avg de colonnes d'une autre table .. ses erreurs donnant

UPDATE college_rating,products set 
property1_avg = avg(college_rating.rating1), 
property2_avg = avg(college_rating.rating2), 
property3_avg = avg(college_rating.rating3), 
property4_avg = avg(college_rating.rating4), 
property5_avg = avg(college_rating.rating5), 
property6_avg = avg(college_rating.rating6), 
property7_avg = avg(college_rating.rating7), 
property8_avg = avg(college_rating.rating8), 
property9_avg = avg(college_rating.rating9), 
property10_avg = avg(college_rating.rating10), 
property11_avg = avg(college_rating.rating11), 
property12_avg = avg(college_rating.rating12), 
property13_avg = avg(college_rating.rating13), 
property14_avg = avg(college_rating.rating14), 
property15_avg = avg(college_rating.rating15) 
where products.alias = concat(college_rating.property1,'-',college_rating.property2,'-',college_rating.property3) 
group by college_rating.property1,college_rating.property2, college_rating.property3 

Answer 1

La syntaxe de mise à jour multi-table de MySQL ne permet pas l'utilisation de group by.

Vous pouvez accomplir ce que vous essayez de faire en déplaçant l'agrégation dans une sous-requête et en vous joignant à cette sous-requête dans la mise à jour multi-tables.

Quelque chose comme cela devrait fonctionner:

update products p 
inner join (
    select concat(property1,'-',property2,'-',property3) as alias, 
    avg(rating1) as property1_avg, 
    avg(rating2) as property2_avg, 
    avg(rating3) as property3_avg, 
    avg(rating4) as property4_avg, 
    avg(rating5) as property5_avg, 
    avg(rating6) as property6_avg, 
    avg(rating7) as property7_avg, 
    avg(rating8) as property8_avg, 
    avg(rating9) as property9_avg, 
    avg(rating10) as property10_avg, 
    avg(rating11) as property11_avg, 
    avg(rating12) as property12_avg, 
    avg(rating13) as property13_avg, 
    avg(rating14) as property14_avg, 
    avg(rating15) as property15_avg 
    from college_rating 
    group by property1,property2, property3 
) as r on r.alias = p.alias 
set p.property1_avg = r.property1_avg, 
p.property2_avg = r.property2_avg, 
p.property3_avg = r.property3_avg, 
p.property4_avg = r.property4_avg, 
p.property5_avg = r.property5_avg, 
p.property6_avg = r.property6_avg, 
p.property7_avg = r.property7_avg, 
p.property8_avg = r.property8_avg, 
p.property9_avg = r.property9_avg, 
p.property10_avg = r.property10_avg, 
p.property11_avg = r.property11_avg, 
p.property12_avg = r.property12_avg, 
p.property13_avg = r.property13_avg, 
p.property14_avg = r.property14_avg, 
p.property15_avg = r.property15_avg; 

Answer 2

Quelle est l'erreur vous obtenez? Et vous devez avoir une clause WHERE sauf si vous voulez que la requête UPDATE s'applique à TOUS les enregistrements

Answer 3

Je pense que vous auriez besoin d'utiliser des sous-requêtes, et je ne suis pas sûr si vous pouvez mettre à jour deux tables comme ça dans MySQL, du moins pas sans préfixer les attributs.