Sql ct（不存在）；概括起来很复杂。感谢您提供的资源（更多学习，呸！）。然而，虽然标记模式没有像它可能的那样正常化，但它也不是EAV。我假设称为PRODUCT_TAG_TYPE_FREE_TAG的条件常量是混淆事物并推断EAV设计的原因，但用户无法控制此列的值

ct（不存在）；概括起来很复杂。感谢您提供的资源（更多学习，呸！）。然而，虽然标记模式没有像它可能的那样正常化，但它也不是EAV。我假设称为PRODUCT_TAG_TYPE_FREE_TAG的条件常量是混淆事物并推断EAV设计的原因，但用户无法控制此列的值。但常量的名称肯定是不明确的！（你可以把这归咎于之前的代码猴子；我在这个项目中继承了很多“怪癖”。）

   select 
      distinct p2c.product_id 
   from '.TABLE_PRODUCT_TO_CATEGORY.' p2c
      inner join '.TABLE_PRODUCT.' p on p2c.product_id = p.id 
      inner join '.TABLE_PRODUCT_TAG.' pt on p.id = pt.product_id
      inner join '.TABLE_TAG_TYPE.' tt on pt.tag_type_id = tt.id
   where 
      tt.id = '.PRODUCT_TAG_TYPE_FREE_TAG.'
      and p.status = 1
      and lower(pt.value) = "cats"
      and lower(pt.value) = "kittens"

   select 
      distinct p2c.product_id 
   from '.TABLE_PRODUCT_TO_CATEGORY.' p2c
      inner join '.TABLE_PRODUCT.' p on p2c.product_id = p.id 
      inner join '.TABLE_PRODUCT_TAG.' pt on p.id = pt.product_id
      inner join '.TABLE_PRODUCT_TAG.' pt2 on p.id = pt2.product_id
      inner join '.TABLE_TAG_TYPE.' tt on pt.tag_type_id = tt.id
   where 
      tt.id = '.PRODUCT_TAG_TYPE_FREE_TAG.'
      and p.status = 1
      and lower(pt.value) = "cats"
      and lower(pt2.value) = "kittens"

select 
  distinct p2c.product_id
from '.TABLE_PRODUCT_TO_CATEGORY.' p2c
  inner join '.TABLE_PRODUCT.' p on p2c.product_id = p.id
  inner join '.TABLE_PRODUCT_TAG.' pt on p.id = pt.product_id
  inner join '.TABLE_TAG_TYPE.' tt on pt.tag_type_id = tt.id   
where 
  tt.id = '.PRODUCT_TAG_TYPE_FREE_TAG.'
  and p.status = 1  
  and (lower(pt.value) = "cats" or lower(pt.value) = "kittens")

and lower(pt.value) = "cats"
and lower(pt.value) = "kittens"

and lower(pt.value) in ("cats","kittens")

  and lower(pt.value) = "cats"
  and lower(pt.value) = "kittens"

and lower(pt1.value) = "cats"
and lower(pt2.value) in ("kittens", "dogs")
and not exists (select * from '.TABLE_PRODUCT_TAG.' pt3 where pt3.product_id = p.id and lower(pt3.value) = "parrots")

SELECT ...
FROM P
WHERE p.status = 1
  AND p.ProductID IN (SELECT Product_ID FROM tags WHERE value = "cats")
  AND p.ProductID IN (SELECT Product_ID FROM tags WHERE value = "kittens")

select 
  distinct p2c.product_id 
from '.TABLE_PRODUCT_TO_CATEGORY.' p2c
  inner join '.TABLE_PRODUCT.'     p  on p2c.product_id = p.id 
where 
  and p.status = 1
  and 2 = (
      SELECT  COUNT(1)
      FROM '.TABLE_PRODUCT_TAG.' pt
        INNER JOIN  '.TABLE_TAG_TYPE.' tt ON pt.tag_type_id = tt.id
      WHERE tt.id = '.PRODUCT_TAG_TYPE_FREE_TAG.'
      AND pt.product_id = p.id /* edit */
      lower(pt.value) IN( "cats", "kittens" )
)