场景查询

Question

我必须执行一个如下所示的查询；

Col_1 Col_2  Col_3  Col_4  Col_5
A       AB    AC     AD     AE
B       BC    BD     BE     ? 
C       CD    CE      ?      ?
D       DE     ?       ?      ?
E        ?     ?       ?      ?

非常感谢对以下内容的任何帮助。

谢谢，阿米特

Answer 1

{

SELECT CHR(64+LEVEL) AS A,
DECODE(SIGN( 4 - LEVEL ) , -1, '?',CHR(64+LEVEL)||CHR(65 +LEVEL)) B,
DECODE(SIGN( 3 - LEVEL ) , -1, '?',CHR(64+LEVEL)||CHR(66 +LEVEL)) C,
DECODE(SIGN( 2 - LEVEL ) , -1, '?',CHR(64+LEVEL)||CHR(67 +LEVEL)) D,
DECODE(sign( 1 - level ) , -1, '?',chr(64+level)||chr(68 +level)) E
 from dual connect by level <6;

} 以上是使用oracle 10g，其他db应该有其他策略。

Answer 2

每列需要不同的rows：

select
   col_1
  ,col_1 || min(col_1) over (order by ... rows between 1 following and 1 following)
  ,col_1 || min(col_1) over (order by ... rows between 2 following and 2 following)
  ,col_1 || min(col_1) over (order by ... rows between 3 following and 3 following)
  ,col_1 || min(col_1) over (order by ... rows between 4 following and 4 following)

场景查询

Query for the scenario

teradata