使用 Oracle SQL 查询进行数据转置

Question

我有 table 和如下数据，

Create table transpose (a number, b number, c number); 

insert into transpose values (1,4,7);
insert into transpose values (2,5,8); 
insert into transpose values (3,6,9); 
commit; 
select * from transpose; 

A B C 
1 4 7 
2 5 8 
3 6 9

问题：我需要使用 sql 查询得到以下输出，这是否可能检索数据（转置数据）？

请帮忙解决这个问题。

Answer 1

有两件重要的事情需要考虑。

1) SQL table 没有隐含的顺序，所以你必须添加 order by 信息来唯一定义转置的列 table。（我在table中添加了一个列ID来模拟它）。

2) 如果您正在寻找固定数量的列和行的解决方案，您可以在 SQL 查询中对结果进行编码，请参见下文（对于动态解决方案，我不建议使用 SQL)

 select 
   (select a from transpose where id = 1) a,
   (select a from transpose where id = 2) b,
   (select a from transpose where id = 3) c
 from dual
 union all
 select 
   (select b from transpose where id = 1) a,
   (select b from transpose where id = 2) b,
   (select b from transpose where id = 3) c
 from dual
 union all
 select 
   (select c from transpose where id = 1) a,
   (select c from transpose where id = 2) b,
   (select c from transpose where id = 3) c
 from dual;

.

     A          B          C
 ---------- ---------- ----------
     1          2          3 
     4          5          6 
     7          8          9

更新 - PIVOT

的解决方案

正如@WW 在此处提出的带有枢轴的解决方案

 with trans as (
 /* add one select for each column */
 select id, 'A' col_name, a col_value from transpose union all
 select id, 'B' col, b col_value from transpose union all
 select id, 'C' col, b col_value from transpose)
 select * from trans
 PIVOT (sum(col_value) col_value 
 for (id) in 
 (1 as "C1", /* add one entry for each row (ID) */
 2 as "C2",
 3 as "C3" )
 )

使用 Oracle SQL 查询进行数据转置

Data transpose using Oracle SQL query

sql

oracle

string-concatenation