SQLite查询重复记录

Question

我创建了两个包含以下记录的表。

CREATE TABLE ForgeRock
    (`id` int,`sta` int, `productName` varchar(7), `description` varchar(55));

INSERT INTO ForgeRock
    (`id`,`sta`, `productName`, `description`)
VALUES
    (1, 0,'OpenIDM', 'Platform for building enterprise provisioning solutions'),

(2,0, 'OpenAM', 'Full-featured access management'),
(3,0, 'OpenDJ', 'Robust LDAP server for Java');


CREATE TABLE ForgeRock1
(`id` int,`sta` int, `productName` varchar(7), `description` varchar(55));

INSERT INTO ForgeRock1
(`id`,`sta`, `productName`, `description`)

VALUES

(1, 2,'hii', 'Platform for building enterprise provisioning solutions'),
(2,0, 'OpenAM', 'Full-featured access management'),
(3,0, 'OpenDJ', 'Robust LDAP server for Java');

我希望联合两个表，但希望记录重复ID为sta = 2

SELECT id,sta
    FROM ForgeRock
    GROUP BY id
    UNION 
   SELECT id, sta 
    FROM ForgeRock1
    GROUP BY id

结果：

id sta 1 0 2 0 3 0 1 2

预期结果：

id sta 1 2 2 0 3 0

Answer 1

在 UNION之后进行分组，并使用MAX（）选择要为每个组输出的行：

SELECT id, MAX(sta) AS sta
FROM (SELECT id, sta
      FROM ForgeRock
      UNION
      SELECT id, sta
      FROM ForgeRock1)
GROUP BY id
ORDER BY id