双重否定SQL查询 [英] Double negation sql query

问题描述

我被要求使用双重否定在sql中进行查询.问题本身就是要求所有"sigla"和"disciplina"，其中semestre_id为21，并且至少具有1个属性"resposta" = 5

I was asked to do a query in sql using double negation. The question itself is asking for all the "sigla" and "disciplina "where the semestre_id is 21 and has at least 1 attribute "resposta"=5

表

查询

现在尽管发布了所有这些信息，但我的大部分问题仍然是我不太确定这是否是在sql中执行正确的双重否定的方法，因为我得到的是表中所有行的答案，这是错误的.由于我很难在网上搜索示例，因此有人可以澄清一下吗?

Now despite posting all this my question is mostly that I am not too sure if this is the way of doing a proper double negation in sql, since I am getting as an answer all the lines of the table which is wrong. Since I am having an hard time searching for examples online could anyone clarify me?

推荐答案

select  disc.disciplina_id, disc.sigla
from    ipdw_disciplina disc
        inner join ipdw_respostas resp
            on disc.disciplina_id = resp.disciplina_id
where   resp.semestre_id = 21
        and resp.resposta = 5
group by disc.disciplina_id, disc.sigla

我尽可能地避免进入/不进入.没有它们，遵循查询的意图似乎更容易.这看起来像一个非常简单的查询，不需要双重否定.

i try to avoid in / not in whenever possible. It seems easier to follow the intent of the query without them. This looks like a pretty straight forward query that does not need the double negation.

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