SELECT sql语句，该语句从表中检索一行，并从另一表中检索许多相关行

Question

我在投票脚本中工作，我有两个表{hs_questions_q} {hs_answers_ans}，第一个存储问题，第二个存储答案

我用这个SQL语句来检索数据

SELECT * FROM hs_questions_q INNER JOIN hs_answers_ans ON id_q=idq_ans WHERE active_q ='1' and home_q ='1' ORDER BY id_q DESC limit 1

我想知道的是，我无法在我的PHP代码中处理的是此查询如何仅从问题表和答案表中返回最后一行，但是我需要从问题表和所有相关行中检索最后一行从答案表到它

Answer 1

这将在表格中为每个问题返回1行，而不是答案的num行：

我假设结构：

hs_questions_q (id,desc)

hs_answers_ans(id,desc)

SELECT question.desc, group_concat(hs_answers_ans.desc SEPARATOR '#')
FROM (select * 
          from hs_questions_q 
          where active_q ='1' and home_q ='1' ORDER BY id_q DESC limit 1) question
INNER JOIN hs_answers_ans ON id_q=idq_ans
group by question.id

result:
question1 | Answer1#Answer2#Answer3

稍后，您可以在php端检索结果后用“＃”分隔。

如果超出允许的数据包大小，您可能会得到截断的答案。 你可以解决

SET SESSION group_concat_max_len = 6000(any threshold); 

Answer 2

我认为这大致就是您要寻找的东西：

SELECT * FROM 
         (select * 
          from hs_questions_q 
          where active_q ='1' and home_q ='1' ORDER BY id_q DESC limit 1) question
 INNER JOIN hs_answers_ans ON id_q=idq_ans

我不知道active_q和home_q是否属于问题表或答案

Answer 3

这是因为您试图获取一行并将其与多于一行的不同数据结合在一起……我认为这行不通。

我会选择问题，然后使用问题中的ID分别获取所有答案。

Answer 4

select * from hs_answer_ans where idq_ans in (select id_q from hs_questions_q where active_q ='1' and home_q ='1' ORDER BY id_q DESC limit 1)

抱歉，评论中有错字... :)

Answer 5

此查询应为您提供所需的结果：

SELECT * 
FROM `hs_questions_q` 
INNER JOIN `hs_answers_ans` ON `id_q` = `idq_ans` 
WHERE `idq_ans` = (
    SELECT MAX(`id_q`)
    FROM `hs_questions_q`
    WHERE `active_q` ='1'
    AND `home_q` ='1'
    );

希望能帮助到你！