如何创建一个 SQL 查询来检查多个表中的重复项

Question

我想创建一个 SQL 查询，用于检查多个不同的 table 中是否存在重复项。我在 Teradata 中这样做。我希望输出如下所示。

|Table A| |Table B| |Table C| |Table D| |Table D|

对于这些列中的每一列，我们可以获得值 Y 或 N。

(Y means that duplicates exist, N means that duplicates does not exist).

我如何创建这个脚本我已经设法编写了如何在 table:

中检查重复项的代码

SELECT  Customer_Id, Year_Month_Id, count(*)
FROM    A
GROUP BY 1,2
HAVING count(*)>1)

Answer 1

编辑#2：

 SELECT
 *
 FROM

     (SELECT
    CASE WHEN MAX(cnt) >1 THEN 'Y' ELSE 'N' END AS [Table1]
        FROM
        (
        SELECT 
        customer_id,
        year_month_id,
        COUNT (*) AS Cnt
        FROM
        table1
        GROUP BY 1,2
        ) tbl1 
    ) t1
CROSS JOIN
     (SELECT
    CASE WHEN MAX(cnt) >1 THEN 'Y' ELSE 'N' END AS [Table2]
        FROM
        (
        SELECT 
        customer_id,
        year_month_id,
        COUNT (*) AS Cnt
        FROM
        table2
        GROUP BY 1,2
        ) tbl2
    ) t2

编辑：在单个 table:

中查找重复项

select
customer_id,
year_month_id,
case when cnt >1 then 'Y' else 'N' end
from
(
select 
customer_id,
year_month_id,
count (*) as Cnt
from
table1
group by 1,2
) t

如果您要查找两个 table 之间的重复项，我可能会使用 union all，如下所示：

 select
    customer_Id,
    year_month_id
    case when count(*) > 1 then 'Y' else 'N' end
    from
    (
    select distinct
    customer_id,
    year_month_id
    from
    table1
    group by 1,2
    UNION ALL
    select distinct
    customer_id,
    year_month_id
    from
    table2 )t 
    group by 1,2

如何创建一个 SQL 查询来检查多个表中的重复项

How to create an SQL query that checks for duplicates in multiple tables

sql

teradata