SQL 查询 - 不为空答案

【问题标题】：SQL query - not nullSQL 查询 - 不为空
【发布时间】：2021-07-08 13:16:42
【问题描述】：

我有sql查询：

Select id
    ,MAX(CASE WHEN (pos = "10") THEN date ELSE NULL END) position10
    ,MAX(CASE WHEN (pos = "18") THEN date ELSE NULL END) position18
    ,MAX(CASE WHEN (pos = "20") THEN date ELSE NULL END) position20
    
FROM table
WHERE 
date BETWEEN "${od=2021-05-01 00:00:01}" AND "${do=2021-07-01 00:00:01}"
AND pos IN('10','18','20')
group by id

我有这张桌子

id	position10	position20	position30
1	2021-05-02	2021-05-02	2021-05-3
2	2021-05-15	2021-05-16	2021-05-18
3	2021-07-08	NULL	NULL

而且我想要不拾取 NULL 值的行。试试这个：

SELECT * FROM (
Select id
        ,MAX(CASE WHEN (pos = "10") THEN date ELSE NULL END) position10
        ,MAX(CASE WHEN (pos = "18") THEN date ELSE NULL END) position18
        ,MAX(CASE WHEN (pos = "20") THEN date ELSE NULL END) position20
        
    FROM table
    WHERE 
    date BETWEEN "${od=2021-05-01 00:00:01}" AND "${do=2021-07-01 00:00:01}"
    AND pos IN('10','18','20')
    group by id )T 
WHERE (position10 IS NOT NULL)
       OR (position18 IS NOT NULL)
       OR (position20 IS NOT NULL)

但它仍然会选择 NULL 值出现在某处的位置。

【问题讨论】：

在哪里（位置 10 不为空）和（位置 18 不为空）和（位置 20 不为空）
用 AND 替换 OR？
天哪，我很愚蠢 :D 我什至没有给我这里的问题。谢谢

标签： sql impala

【解决方案1】：

您需要在WHERE 子句中将OR 更改为AND

SELECT * FROM (
Select id
        ,MAX(CASE WHEN (pos = "10") THEN date ELSE NULL END) position10
        ,MAX(CASE WHEN (pos = "18") THEN date ELSE NULL END) position18
        ,MAX(CASE WHEN (pos = "20") THEN date ELSE NULL END) position20
        
    FROM table
    WHERE 
    date BETWEEN "${od=2021-05-01 00:00:01}" AND "${do=2021-07-01 00:00:01}"
    AND pos IN('10','18','20')
    group by id )T 
WHERE position10 IS NOT NULL
       AND position18 IS NOT NULL
       AND position20 IS NOT NULL

【讨论】：