Check if Values of one column in another column of different table

问题

I am new to SQL and struck with this below scenario, can any one of you please help on this.

I want to check if the ingredients of a product allowed on production line if so then production line names for the product where it can be produced.

Table 1

ProductionLine       Allergen
  BB1          Tree nut
  BB1          Peanut
  BB1           Milk
  BB1           Wheat
  BB2          Tree nut
  BB2          Peanut
  BB2           Milk 
  BB2           soy
  BB2           Egg

Table 2

Product                Ingredients
P1                 Tree nut
P1                 Peanut
P1                 Milk 
P1                 soy

Here the Product P1 can be produced on BB2 line as all the ingredients are allowed on BB2 Allergen list. so i want to have the result set as

Expected Result

  Product            Ingredients          ProductionLine
  P1                 Tree nut                 BB2
  P1                 Peanut                   BB2
  P1                 Milk                     BB2   
  P1                 soy                      BB2

If any one of the ingredient is not allowed on any line then we can not produce product on that line.

回答1:

Assuming there are no duplicates in either table, you can use a left join and group by. The key is counting the number of matches and being sure that it matches the total number of ingredients.

select t2.product, t1.productionline
from (select t2.*,
             count(*) over (partition by product) as num_products
      from table2 t2
     ) t2 left join
     table1 t1
     on t2.ingredient = t1.allergen
group by t2.product, t1.productionline, t2.num_products
having count(t1.ingredient) = num_products;

回答2:

So, ideally the Allergen would have some ID that you can join on so you could do something like

SELECT Table2.Product, Table2.Ingredients, Table1.ProductionLine FROM Table1.AllergenId JOIN Table2.IngredientAllergenId

If your tables aren't structured like this, they probably should be. But if you can't change it, you can do this.

SELECT Table2.Product, Table2.Ingredients, Table1.ProductionLine FROM Table1.Allergen JOIN Table2.Allergen

来源：https://stackoverflow.com/questions/57775400/check-if-values-of-one-column-in-another-column-of-different-table

标签

sql

sql-server

mssql-jdbc