sql - 如何从文件中删除重复项，同时某些字段优先？

Question

所以我有 SQL，如果检测到重复项，它会向字段添加代码。还有一个字段叫 DS

DS 可以是"is"，也可以是“否”

如果发现重复项，我怎样才能做到"is"不编码而“否”编码？

本质上"is"优先。

我的 SQL:

WITH cte
     AS (SELECT *,
                Row_Number() OVER(partition BY fips_county_code, last, suffix, first, birthdate Order by (select null)) AS Rn
         FROM   [PULLED REC])
UPDATE cte
SET    BAD_CODES = Isnull(BAD_CODES, '') + 'D'
WHERE  RN > 1; 

Answer 1

要仅更新 ds='No' 的行，您可以将其添加到 where 子句中。

为了确保 rn > 1 不会跳过需要更新的重复项之一，您可以使用 exists() 替代 count( )

with cte as (
  select   
      *
    , rn = row_number() over (
            partition by fips_county_code, last, suffix, first, birthdate
            order by (case when DS = 'yes' then 0 else 1 end) asc
            )
    from [pulled rec]
)
/* -- check with select first -- */
select * from cte

/* 
update cte set 
    bad_codes = isnull(bad_codes, '') + 'D'
--*/
/* -- Update all records that have a duplicate 
  -- except the First row, ordered by ds='Yes' first */
/*
  where cte.ds = 'No'
    and cte.rn > 1
--*/ 
-- Update all records that have a duplicate and ds='No' --
--/*
  where cte.ds = 'No'
    and exists (
      select 1
        from cte as i
        where i.rn > 1
          and i.fips_county_code = cte.fips_county_code
          and i.last = cte.last
          and i.suffix = cte.suffix
          and i.first = cte.first
          and i.birthdate = cte.birthdate
      );
--*/

使用 count() over() 的替代版本:

with cte as (
  select   
      *
    , CountOver = count() over (
            partition by fips_county_code, last, suffix, first, birthdate
            )
    from [pulled rec]
)
/* -- check with select first -- */
select * from cte

/* 
update cte set 
    bad_codes = isnull(bad_codes, '') + 'D'
--*/

  where cte.ds = 'No'
    and cte.CountOver > 1