多對多關系中的sql查詢返回單個記錄

Question

如何獲得project_id，它具有一行一行的tech_id = 1和technology_id = 2？

+------------+---------------+
| project_id | technology_id |
+------------+---------------+
|          1 |             1 |
|          1 |             2 |
|          3 |             2 |
|          7 |             1 |
|          9 |             1 |
+------------+---------------+

Answer 1

本集團product_id ，並采取只有那些群體同時具有technology_id小號

select project_id
from your_table
where technology_id in (1,2)
group by project_id
having count(*) = 2