从 sql 中的组中选择文本值

Question

如果该组中存在该特定字符串，我想选择该行

我有一个包含 id 和 detail 列的表。

查询创建表：

create table emp_detail (id number,details varchar2(20));
insert into emp_detail values(12,'Major')
insert into emp_detail values(12,'Critical')
insert into emp_detail values(12,'high')
insert into emp_detail values(12,'Low')
insert into emp_detail values(13,'Major')
insert into emp_detail values(13,'Low')
insert into emp_detail values(13,'high')
insert into emp_detail values(14,'Critical')
insert into emp_detail values(14,'Low')
insert into emp_detail values(14,'high')

查询结果：

Id     Detail
12  Major
12  Critical
12  high
12  Low

13  Major
13  Low
13  high

14  Critical
14  Low
14  high

预期输出

Id     Detail
12  Critical
13  Major
14  Critical

因此，如果 id 的详细信息中同时存在关键和主要，那么我想选择仅关键。如果没有关键，则选择主要。如果只有关键，则将选择关键。

Answer 1

这是一个优先级查询。你可以使用row_number():

select id, details
from (select ed.*,
             row_number() over (partition by id
                                order by (case details when 'Critical' then 1 when 'Major' then 2 when 'High' then 3 when 'Low' then 4 else 5
                               ) as seqnum
      from emp_detail ed
     ) ed
where seqnum = 1;

您也可以使用join：

select id, details
from (select ed.*,
             row_number() over (partition by id
                                order by d.ord nulls last
                               ) as seqnum
      from emp_detail ed left join
           (select 'Critical' as details, 1 as ord from dual union all
            select 'Major' as details, 2 as ord from dual union all
            select 'High' as details, 3 as ord from dual union all
            select 'Low' as details, 4 as ord from dual union all
           ) d
           on ed.details = d.details

     ) ed
where seqnum = 1;

最后，解决此问题的一种有趣方法是使用聚合和coalesce()：

select id,
       coalesce( max(case when details = 'Critical' then details end),
                 max(case when details = 'Major' then details end),
                 max(case when details = 'High' then details end),
                 max(case when details = 'Low' then details end)
               ) as details
from emp_details ed
group by id;

注意：由于某种原因，'high' 不遵循您的大小写约定，因此请修复数据或使用'high' 进行上述查询。

Answer 2

使用row_number() 和length()

select id,detail from 
(select id,detail,row_number() over(partition by id order by length(Detail) desc) rn
from table_name
) a where a.rm=1

Answer 3

试试这个-

SELECT ID,
CASE 
    WHEN Detail = 4 THEN 'Critical'
    WHEN Detail = 3 THEN 'Major'
    WHEN Detail = 2 THEN 'High'
    WHEN Detail = 1 THEN 'Low'
END Detail
FROM
(
    SELECT ID,
    MAX(
    CASE 
        WHEN Detail = 'Critical' THEN 4
        WHEN Detail = 'Major' THEN 3
        WHEN Detail = 'High' THEN 2
        WHEN Detail = 'Low' THEN 1
    END Detail 
    )
    FROM your_table
    GROUP BY ID
)A

Answer 4

您可以使用MAX( details ) KEEP ( DENSE RANK FIRST ORDER BY ... ) 并使用CASE 语句设置排序首选项：

Oracle 设置：

create table emp_detail (id, details ) AS
  SELECT 12, 'Major'    FROM DUAL UNION ALL
  SELECT 12, 'Critical' FROM DUAL UNION ALL
  SELECT 12, 'High'     FROM DUAL UNION ALL
  SELECT 12, 'Low'      FROM DUAL UNION ALL
  SELECT 13, 'Major'    FROM DUAL UNION ALL
  SELECT 13, 'High'     FROM DUAL UNION ALL
  SELECT 13, 'Low'      FROM DUAL UNION ALL
  SELECT 14, 'Critical' FROM DUAL UNION ALL
  SELECT 14, 'High'     FROM DUAL UNION ALL
  SELECT 14, 'Low'      FROM DUAL;

查询：

SELECT id,
       MAX( details )
         KEEP (
           DENSE_RANK FIRST
           ORDER BY CASE details
                    WHEN 'Critical' THEN 1
                    WHEN 'Major'    THEN 2
                    WHEN 'High'     THEN 3
                    WHEN 'Low'      THEN 4
                                    ELSE 5
                    END
         ) AS details
FROM   emp_detail
GROUP BY id

输出：

身份证 |细节 -: | :-------- 12 |危急 13 |主要的 14 |危急

db小提琴here