SQL 删除某些重复值

Question

我有这样的结果 table（在查询运行之后）：

     id     |  time  | region
12x-4nm-334 | 16:00  | Utah
12x-4nm-334 | 17:00  | California
12x-4nm-334 | 19:00  | Missouri
12x-4nm-334 | 22:00  | California
983-n2n-aq2 |  8:00  | New York
983-n2n-aq2 |  9:00  | New York

这个table中还有一些其他的列，但重要的是我想从结果中删除只注册到一个区域的id。因此，像“983-n2n-aq2”这样只出现在单个区域（无论时间如何）的 ID 不应该出现在结果 table.

中

希望这个问题够清楚了。

Answer 1

试试这个：

SELECT id, count(DISTINCT region) as RegionCount
FROM table
GROUP BY
    id
HAVING count(DISTINCT region) > 1

如果您的 DBMS 不支持 count(distinct ) 那么应该这样做：

SELECT id, count(DISTINCT region) as RegionCount
FROM (
    SELECT id, region FROM table GROUP BY id, region
) as table
GROUP BY
    id
HAVING count(DISTINCT region) > 1

Answer 2

如果你使用MySql

    DELETE FROM table 
    WHERE id IN (   SELECT x.id
                    FROM (  select *
                            FROM table t
                            GROUP BY id
                            HAVING COUNT(DISTINCT region) = 1
                           ) as x
                    )

我不知道 Vertica。希望对你有帮助

Answer 3

试试这个（从 Geerkens 先生那里借来的）：

SELECT a.*
FROM table a INNER JOIN
(
    SELECT id
    FROM table
    GROUP BY id
    HAVING count(DISTINCT region) > 1
) b ON a.id = b.id

Answer 4

首先获取具有多个不同区域的id（如子查询中所示），然后在WHERE子句中使用它进行过滤。

SELECT id, time, region
FROM mytable
WHERE id IN
(
    SELECT id
    FROM mytable
    GROUP BY id
    HAVING count(DISTINCT region) > 1
)

SQL 删除某些重复值

SQL remove certain duplicate values

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vertica