比較與Postgresql的兩種關系

Question

我正在通過連接表比較兩個條目並返回匹配的百分比

聯接表如下所示：

|recipe_id|ingredient_id|
|---------|-------------|
|    1    |      1      |
|    1    |      2      |
|    1    |      3      |
|-----------------------|
|    2    |      4      |
|    2    |      10     |
|    2    |      20     |
|-----------------------|

如果我提供了一個數組ingredient_id => [1,2,3] ，則預期結果為

|recipe_id|match_percent|
|---------|-------------|
|    1    |      100    |
|-----------------------|
|    2    |      0      |
|-----------------------|

我該如何實現？

Answer 1

我的建議是將數組作為查找表，並與之連接以查找計數

select t.recipe_id, 
count(t.ingredient_id)/(select count(*) from lookup_table)*100 as match_percent 
from
(
select t1.recipe_id,t1.ingredient_id from table as t1 inner join lookup_table as t2
on t1.ingredient_id=t2.ingredient_id
) as t 
group by t1.recipe_id