sql过滤多列答案

【问题标题】：sql filter on multiple columnssql过滤多列
【发布时间】：2021-03-16 08:11:54
【问题描述】：

树：

id name
1  apple
2  aspen

树属性类别：

id categorie
1  leafColour
2  trunkColour

树属性：

id tree_id attribute tree_attribute_categorie_id
1  1       brown     1
2  1       brown     2
3  2       green     1
4  2       brown     2

sql 语句如何过滤如下（属性和 tree_attribute_categorie_id）：

[[brown and 1] OR [red and 1]] AND [[brown and 2] OR [green and 2]] = return apple tree
[[brown and 1] OR [green and 1]] AND [[brown and 2] OR [green and 2]] = returns both trees

【问题讨论】：

标签： mysql sql inner-join aggregate-functions having-clause

【解决方案1】：

您可以使用group by 和having：

select t.*
from tree t
inner join treeattributes ta on ta.tree_id = t.id
group by t.id
having max(ta.tree_attribute_categorie_id = 1 and ta.attribute in ('brown', 'red')) = 1
   and max(ta.tree_attribute_categorie_id = 2 and ta.attribute in ('brown', 'green')) = 1

这符合您问题中的第一个过滤器规范。第二个规范的 having 子句如下所示：

having max(ta.tree_attribute_categorie_id = 1 and ta.attribute in ('brown', 'green')) = 1
   and max(ta.tree_attribute_categorie_id = 2 and ta.attribute in ('brown', 'green')) = 1

如果您想按属性名称而不是按属性 id 进行过滤，您可以再添加一个连接，并调整 having 子句：

select t.*
from tree t
inner join treeattributes ta on ta.tree_id = t.id
inner join treeattributecategori tag on tag.id = ta.tree_attribute_categorie_i
group by t.id
having max(tag.categorie = 'leafColour' and ta.attribute in ('brown', 'red')) = 1
   and max(tag.categorie = 'trunkColour' and ta.attribute in ('brown', 'green')) = 1

【讨论】：