Mysql Many-to-many (AND Where) select

Question

i have this database setup:

• products

  • id
  • [fields...]

• tags

  • id
  • [fields...]

• product_tag

  • id
  • product_id
  • tag_id

If have this records in my database

• Products
  • Product A [id: 1]
  • Product B [id: 2]
  • Product C [id: 3]

---

• Tags
  • Tag A [id: 1]
  • Tag B [id: 2]
  • Tag C [id: 3]

---

• Produc_Tag
  • [product_id: 1, tag_id: 1]
  • [product_id: 1, tag_id: 2]
  • [product_id: 2, tag_id: 1]
  • [product_id: 2, tag_id: 3]
  • [product_id: 3, tag_id: 1]
  • [product_id: 3, tag_id: 2]

---

How do i query to get the products that have tag_id 1 AND 2 (it must by products with tag_id 1 AND 2) in this example: "Product A" and "Product C"

Answer 1

SELECT *
FROM products
WHERE id IN (
    SELECT product_id
    FROM product_tag
    GROUP BY product_id
    HAVING GROUP_CONCAT(tag_id) = '1,2'
)

Answer 2

Use this

SELECT P.id
FROM products P
INNER JOIN products_tags PT ON PT.product_id = P.id
WHERE PT.tag_id IN (1,2)
GROUP BY P.id
HAVING COUNT(PT.*) = 2