SQL：比较两个表

Question

您好，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)，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_id。

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，您可以尝试执行以下操作：

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，如果你只是想知道每个 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，一个表中不存在另一个表中不存在的元组，您将需要使用这个：

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;

或者如果你想知道一个表中存在的元组而不是另一个你可以使用的元组：

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

基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
        )