如何从同一个表中选择具有多个别名的同一列？

Question

我需要使用以下组合从表中选择值

SELECT Details FROM  Avenger   WHERE Id = '1' AND KEY LIKE '11AX';
SELECT Details FROM  Avenger   WHERE Id = '1' AND KEY LIKE '34XA';
SELECT Details FROM  Avenger   WHERE Id = '1' and KEY = '11AZ';
SELECT Details FROM  Avenger   WHERE Id = '1' AND KEY LIKE '11ZA';

在单个查询中我知道我可以使用

SELECT * FROM Avenger WHERE ID='1';

但我需要使用所有选定的值并将其分配给单个查询中的四个变量。

我可以使用任何想法或解决方案吗？

Id  Key Details
1   11AX    Mark 
1   34XA    Bruce 
1   11AZ    Mr. Green
1   11ZA    Hulk
2   11AX    Robert jr.
2   34XA    Toney 
2   11AZ    Iron Man
2   11ZA    Arrogant
3   11AX    Thor
3   34XA    Asgard
3   11AZ    God
3   11ZA    Hamer

Answer 1

我认为我知道你想要这个：

select 
    (SELECT Details FROM  Avenger   WHERE Id = '1' AND KEY LIKE '11AX') as var1,
    (SELECT Details FROM  Avenger   WHERE Id = '1' AND KEY LIKE '34XA') as var2,
    (SELECT Details FROM  Avenger   WHERE Id = '1' and KEY = '11AZ') as var3,
    (SELECT Details FROM  Avenger   WHERE Id = '1' AND KEY LIKE '11ZA') as var4
    from dual

还有一个pivot 选项

Answer 2

我们可以在这里尝试使用REGEXP_LIKE 交替使用：

SELECT *
FROM yourTable
WHERE Id = '1' AND REGEXP_LIKE("KEY", '11AX|34XA|11AZ|11ZA')

实际上，我不确定您是否打算在原始查询中使用 LIKE。你可能真的只想这样做：

SELECT *
FROM yourTable
WHERE Id = '1' "KEY" IN ('11AX', '34XA', '11AZ', '11ZA')

Answer 3

我想你想要一个case 表达式：

select details,
       (case when key like '11AX' then 1
             when key like '34XA' then 2
             when key like '11AZ' then 3
             when key like '11ZA' then 4
        end) as flag
from avenger a
where id = 1;

如果您只想使用单个表达式选择值，请以 in 开头：

where id = 1 and key in ('11AX', '34XA', '11AZ', '11ZA')

如果您想将值作为单个字符串传递，那么 regexp_like() 有效：

where id = 1 and regexp_like(key, '^11AX|34XA|11AZ|11ZA$')

两个音符：

• 模式已锚定，因此仅匹配完整的key。
• regexp_like() 通常不使用索引，因此为了提高性能，= 和 in 是更好的选择。

也许你打算：

select max(case when key like '11AX' then details end) as deails_11ax,
       max(case when key like '34XA' then details end) as details_34XA,
       max(case when key like '11AZ' then details end) as details_11AZ,
       max(case when key like '11ZA' then details end) as details_11AZ
from avenger a
where id = 1;

这将返回一行四列。