我有一个有趣的难题,我认为可以用纯粹的SQL解决.我有类似于以下的表:
responses:
user_id | question_id | body
----------------------------
1 | 1 | Yes
2 | 1 | Yes
1 | 2 | Yes
2 | 2 | No
1 | 3 | No
2 | 3 | No
questions:
id | body
-------------------------
1 | Do you like apples?
2 | Do you like oranges?
3 | Do you like carrots?
我想得到以下输出
user_id | Do you like apples? | Do you like oranges? | Do you like carrots?
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1 …我有一个包含产品订单表的数据库,如下所示:
order_id | prod_code | prod_color | size | quantity |
-----------------------------------------------------
1 SHIRT 001 S 10
1 SHIRT 001 M 7
1 SHIRT 001 L 8
1 SHIRT 001 XL 1
1 SHIRT 995 S 2
1 SHIRT 995 M 1
1 SHIRT 995 L 0
1 SHIRT 995 XL 1
2 PANTS ....
和这样的产品价格表:
prod_code | prod_color | price | currency
-----------------------------------------
SHIRT 001 10 EUR
SHIRT 001 9 USD
SHIRT 001 50 YEN
SHIRT 001 15 RUB …