Question

我在SQL中有这个查询，我知道它写得非常糟糕。你们能帮助我以体面，正常的方式写作吗？

感谢。

select distinct R.*, X.LIKED
from Recipe R
left join (select distinct R.* , '1' as LIKED 
           from Recipe R, Likes L 
           where R.id = L.idRecipe 
             and L.email = 'dvader@deathstar.galacticempire') X
on R.id = X.id

Answer 1

看起来你需要所有来自vader@deathstar.galacticempire喜欢标记的食谱

select R.*, likedR.LIKED
from Recipe R
left join (select distinct R.id , '1' as LIKED 
           from Recipe R 
                inner join Likes L on R.id = L.idRecipe
           where  
                L.email = 'dvader@deathstar.galacticempire') likedR
on R.id = likedR.id

Answer 2

感谢大家的帮助。

我能够通过此查询做我想要的事情：

select distinct R.*, X.LIKED, U.imgUrl 
from  User U, Recipe R 
left join 
    (select distinct R.* , '1' as LIKED 
     from Recipe R, Likes L 
     where R.id = L.idRecipe and L.email = 'dvader@deathstar.ge') X 
on R.id = X.id 
where R.email = U.email

如果dvader的条目在另一个表中，使用连接，这将在一个表中加上我需要的所有信息加1个额外的列，或者为1或者为null。

SQL查询改进（表中的额外列）

2 个答案: