sql - 我怎样才能采用两个单独的 sql 查询的 UNION 并仅获取 DISTINCT 值

Question

如何在 PHP 中从我的这两个查询中仅获取不同的值:

$query1 = "SELECT g.name, g.hash, g.views
                    FROM c7_groups g, c7_groups_affiliations ga
                    WHERE g.category >= 592 AND g.category <= 622
                        AND ga.affiliated_groups_hash = g.hash
                        AND LOWER(g.name) LIKE LOWER('%$school_name%')
                        ";
        $query2 = "SELECT g.name, g.hash, g.views
                    FROM c7_groups g, c7_groups_affiliations ga, c7_affiliations a
                    WHERE ga.affiliations_id = a.id
                        AND ga.groups_hash = g.hash
                        AND LOWER(a.name) LIKE LOWER('%$school_name%')";

我只想从这两个查询中获取不同的“g.hash”。如果我可以使用一个 sql 查询来完成这两项任务，那就更好了。

关于我的数据库表的详细信息如下: c7_groups: id int(10)
名称 varchar(255)
哈希 varchar(32) groups_categories_id int(10) View int(10)

c7_affiliations 标识整数(10) 名称 varchar(100)
groups_categories_id int(10)

c7_groups_affiliations groups_hash varchar(32) affiliated_groups_hash varchar(32)--------FKey to c7_groups.hash
affiliations_id int(10)--------------------FKey to c7_affiliations.id
id int(10)

affiliated_groups_hash 和 affiliations_id 都可以为空，或者我应该说一个或它们总是为空。如果一个组隶属于另一个组，则 affiliations_id 将为空，如果该组隶属于另一个从属关系，则 affiliated_groups_hash 将为空。

如果您需要有关任何内容的更多详细信息，请告诉我。

问候 泽山

Answer 1

只需在子选择中进行并集，然后按派生表进行分组。

select name,count(*) from
(
               SELECT g.name, g.hash, g.views
                    FROM c7_groups g, c7_groups_affiliations ga
                    WHERE g.category >= 592 AND g.category <= 622
                        AND ga.affiliated_groups_hash = g.hash
                        AND LOWER(g.name) LIKE LOWER('%$school_name%')
     UNION
               SELECT g.name, g.hash, g.views
                    FROM c7_groups g, c7_groups_affiliations ga, c7_affiliations a
                    WHERE ga.affiliations_id = a.id
                        AND ga.groups_hash = g.hash
                        AND LOWER(a.name) LIKE LOWER('%$school_name%')";
) as myTbl
group by name