java - SQL：比较两个表

Question

嗨，我有这种情况，我很震惊。

我有两个表，表 A 和表 B，它们有一个共同的主键（panelist_id），并且对于每个 panelist_id，都有许多 entity_id。

我想检查表中是否存在每个 panelist_id 和相同的 entity_ids。

注意：有很多 panelist_id，每个 panelist_id 都有很多 entity_id。

请帮帮我。

Answer 1

要选择仅在其中一个表中可用的 panelist_id/entity_id 元组，请尝试执行以下操作：

select panelist_id, entity_id from
(
  select panelist_id, entity_id from a
  union all
  select panelist_id, entity_id from b
)
group by panelist_id, entity_id
having count(*) = 1;

Answer 2

Select A.panelist_id from tableA as A inner join tableB as B
on A.panelist_id=B.panelist_id
GROUP BY A.panelist_id
HAVING COUNT(DISTINCT A.entity_id)=COUNT(DISTINCT B.entity_id)

Answer 3

我不能确切地知道你在问什么，如果你只想知道每个 Entity_ID/Panelist_ID 元组是否存在于一个或两个表中，那么这将起作用：

SELECT  Panelist_ID, 
        Entity_ID,
        CASE WHEN COUNT(A) > 0 AND COUNT(B) > 0 THEN 'Both Tables'
            WHEN COUNT(B) = 0 THEN 'Table A'
            WHEN COUNT(A) = 0 THEN 'Table B'
        END AS Status
FROM    (   SELECT  Panelist_ID, Entity_ID, 1 AS A, NULL AS B
            FROM    A
            UNION ALL
            SELECT  Panelist_ID, Entity_ID, NULL AS A, 1 AS B
            FROM    B
        ) T
GROUP BY Panelist_ID, Entity_ID;

如果您想知道每个表中的元组相同的 panelist_ID，并且一个表中不存在另一个表中不存在的元组，您将需要使用此：

SELECT  *
FROM    A
        FULL JOIN B
            ON A.Panelist_ID = B.Panelist_ID
            AND A.Entity_ID = B.Entity_ID
WHERE   A.Entity_ID IS NOT NULL
AND     B.Entity_ID IS NOT NULL;

或者，如果您想知道一个表中存在的元组而不是另一个表中的元组，您可以使用：

SELECT  *
FROM    A
        FULL JOIN B
            ON A.Panelist_ID = B.Panelist_ID
            AND A.Entity_ID = B.Entity_ID
WHERE   A.Entity_ID IS NULL
OR      B.Entity_ID IS NULL;

编辑

根据关于只需要验证临时表与永久表相同的评论，您可以使用EXISTS：

SELECT  *
FROM    PermanentTable p
WHERE   NOT EXISTS 
        (   SELECT  1
            FROM    TempTable t
            WHERE   p.Panelist_ID = t.Panelist_ID
            AND     p.Entity_ID = t.Entity_ID
            ... More conditions to help find if entries are missing from temp table
        )