Question

示例：

表Question_Answers：

    +------+--------+
    | q_id | ans_id |
    +------+--------+
    |    1 |      2 |
    |    1 |      4 |
    |    2 |      1 |
    |    3 |      1 |
    |    3 |      2 |
    |    3 |      3 |
    +------+--------+

User_Submited_Answers：

    | q_id | sub_ans_id |
    +------+------------+
    |    1 |          2 |
    |    1 |          4 |
    |    2 |          1 |
    |    3 |          1 |
    |    3 |          2 |
    |    3 |          4 |
    +------+------------+

如果此行匹配count 1 else 0

，我需要一个T-SQL查询

Answer 1

let restaurantLat = restaurants["results"][indexPath.row]["geometry"]!["location"]!!["lat"] as? String

Answer 2

请尝试以下代码：

select qa.q_id,case when qa.ans_id=sqa.ans_id then 1 else 0 end as result from questionans qa
left  join subquestionans sqa
on qa.q_id=sqa.q_id and qa.ans_id=sqa.ans_id

Answer 3

这应该可以为每个问题提供预期的结果。

select q_id, min(Is_Correct)Is_Correct from (
select Q.q_id,case when count(A.sub_ans_id)=count(*) then 1 else 0 end as Is_Correct
from #Q Q left join #A A on Q.q_id=A.q_id and Q.ans_id=A.sub_ans_id
group by Q.q_id
UNION ALL
select A.q_id,case when count(Q.ans_id)=count(*) then 1 else 0 end as Is_Correct
from #Q Q right join #A A on Q.q_id=A.q_id and Q.ans_id=A.sub_ans_id
group by A.q_id ) I group by q_id

Answer 4

MySQL解决方案（sql fiddle）：

SELECT tmp.q_id, MIN(c) as correct
FROM (
    SELECT qa.q_id, IF(qa.q_id = usa.q_id, 1, 0) as c 
    FROM question_answers qa
    LEFT JOIN user_submited_answers usa
      ON qa.q_id = usa.q_id AND qa.ans_id = usa.sub_ans_id
    UNION
    SELECT usa.q_id, IF(qa.q_id = usa.q_id, 1, 0) as c 
    FROM question_answers qa
    RIGHT JOIN user_submited_answers usa
      ON qa.q_id = usa.q_id AND qa.ans_id = usa.sub_ans_id
) tmp
GROUP BY tmp.q_id;

现在，一步一步解释：

为了获得正确的输出，我们需要：

从question_answers表格中提取用户未填写的答案（在您的示例中为q_id = 3 ans_id = 3）
从user_submited_answers表格中提取用户填写的错误答案（在您的示例中为q_id = 3 sub_ans_id = 4）

为此，我们可以使用完全外连接（对于mysql左连接+右连接）：

SELECT *
FROM question_answers qa
LEFT JOIN user_submited_answers usa
  ON qa.q_id = usa.q_id AND qa.ans_id = usa.sub_ans_id
UNION
SELECT *
FROM question_answers qa
RIGHT JOIN user_submited_answers usa
  ON qa.q_id = usa.q_id AND qa.ans_id = usa.sub_ans_id;

从前面的查询结果中，我们要查找的行（错误答案）包含NULL值（基于案例，在question_answers表或user_submited_answers表中）。

下一步是使用IF或CASE语句将这些行标记为0（错误答案）：IF(qa.q_id = usa.q_id, 1, 0)。

要获得最终输出，我们需要按q_id进行分组，并在分组行中查找0个值。如果至少有一个0，则该问题的答案是错误的，应将其标记为。

检查sql小提琴：SQL Fiddle

如果匹配，需要T-SQL查询以获得多项选择答案

4 个答案: