MySQL 查询：使用 UNION 并获取行号作为 SELECT 的一部分

Question

我有一个联合查询如下：

(SELECT t.id, t.name, c.company AS owner, t.creation_date AS date, t.notes
 FROM tool t, client c
 WHERE t.id_customer = '15' AND t.trash_flag = '1')
  UNION
(SELECT f.id, f.name, CONCAT(m.first_name, ' ', m.last_name) AS owner, f.date, f.notes
 FROM file f, meta m
 WHERE ((f.acl = 0) OR (f.acl = 1 AND '1' = TRUE) OR (f.acl = 2 AND f.id = '7')) AND f.id = '15' AND f.trash_flag = '1' AND m.user_id = f.id_user) 
 ORDER BY 'name' 'ASC' LIMIT 0,20

Everything works fine but I have two questions:

1. 如何向整个结果集中添加一个给出行号的列
2. 我可以在不使用 UNION（例如高级联接）的情况下执行此操作吗？

感谢 MySQL 专家们的宝贵时间！

Answer 1

我现在无法测试它，但从我发现的情况来看，以下可能有效：

参考：行号变量

SQL语句

SELECT  @rownum := @rownum + 1 rownum
        , t.*
FROM    (
            (SELECT t.id
                    , t.name
                    , c.company AS owner
                    , t.creation_date AS date
                    , t.notes 
            FROM    tool t
                    , client c 
            WHERE   t.id_customer = '15' 
                    AND t.trash_flag = '1' 
            ) UNION (
            SELECT  f.id
                    , f.name
                    , CONCAT(m.first_name, ' ', m.last_name) AS owner
                    , f.date
                    , f.notes 
            FROM    file f
                    , meta m 
            WHERE   ((f.acl = 0) OR (f.acl = 1 AND '1' = TRUE) OR (f.acl = 2 AND f.id = '7')) AND f.id = '15' AND f.trash_flag = '1' AND m.user_id = f.id_user) 
            )
        ) t
        , (SELECT @rownum := 0) r
ORDER BY 
        'name' ASC
LIMIT   0, 20