Question

所以我有一个这样的表：

ID  DESCRIPTION  AGROUP
-----------------------
1   AN  
2   FI  
3   DOC 1        DOC
4   DOC 2        DOC
5   CO  
6   RI           RI

如果AGROUP列不为空，则我想选择该值并按该值分组，否则，请选择Description；在任何情况下均按ID排序。我想要的结果是：

ID  RESULT
-----------------------
1   AN  
2   FI  
3   DOC
5   CO  
6   RI

我尝试先创建一个子查询，

SELECT 
  DISTINCT (NVL(AGROUP, DESCRIPTION)) AS DES 
FROM 
  temp
GROUP BY NVL(AGROUP, DESCRIPTION)

然后添加外部查询：

SELECT 
    ID,
    DES 
FROM
(
    SELECT DISTINCT (NVL(AGROUP, DESCRIPTION)) AS DES 
        FROM 
    temp
        GROUP BY NVL(AGROUP, DESCRIPTION) 
) T1
JOIN TEMP T2 ON (T1.DES = T2.AGROUP OR T1.DES = T2.DESCRIPTION)
ORDER BY ID
;

但是随后我两次收到DOC：

1   AN
2   FI
3   DOC
4   DOC
5   CO
6   RI

SQL让我大跌眼镜！谢谢。

Answer 1

我认为您只想要group by：

select coalesce(AGROUP, DESCRIPTION) AS DES, min(id) as id
from  temp
group by coalesce(AGROUP, DESCRIPTION);

Answer 2

尝试此代码

SELECT 
DISTINCT (DESCRIPTION)) AS DES 
FROM 
temp
where AGROUP IS NOT NULL
GROUP BY (AGROUP, DESCRIPTION)

SQL分组并在不为null时选择一列

2 个答案: