Question

我有一个相当复杂的遗留sql查询，它为这样的文档选择属性列表：

 type |  name   | attr | int_val |  str_val 
--------------------------------------------
  1   |  doc-1  |  10  |  1003   |   null
  1   |  doc-1  |  15  |  null   |  string1
  2   |  doc-2  |  13  |  1004   |   null
  2   |  doc-2  |  22  |  null   |  string2
  1   |  doc-3  |  10  |  1005   |   null
  1   |  doc-3  |  15  |  null   |  string3

我害怕改变遗留sql中的任何内容，所以我想将现有的输出转换为：

 type |  name  | attr-A | attr-B
----------------------------------
  1   | doc-1  |  1003  | string1
  2   | doc-2  |  1004  | string2
  1   | doc-3  |  1005  | string3

对于type = 1的每个文档：attr-A是attr = 10的属性（使用 int_val），attr-B是属性，attr = 15（使用str_val）
对于type = 2的每个文档：attr-A是attr = 13的属性（使用int_val），attr-B是attr = 22的属性（使用str_val）

请帮我编写以我提议的方式处理现有输出的查询。

Answer 1

您的逻辑可以GROUP BY和CASE WHEN：

SELECT type, name,
    MAX(CASE WHEN type = 1 AND attr = 10 THEN int_val 
             WHEN type = 2 AND attr = 13 THEN int_val
       END) AS AttrA,
    MAX(CASE WHEN type = 1 AND attr = 15 THEN str_val 
             WHEN type = 2 AND attr = 22 THEN str_val 
       END) AS AttrB
FROM your_table
GROUP BY type, name;

的 LiveDemo

输出：

╔══════╦═══════╦═══════╦═════════╗ ║ type ║ name ║ attrA ║ attrB ║ ╠══════╬═══════╬═══════╬═════════╣ ║ 1 ║ doc-1 ║ 1003 ║ string1 ║ ║ 2 ║ doc-2 ║ 1004 ║ string2 ║ ║ 1 ║ doc-3 ║ 1005 ║ string3 ║ ╚══════╩═══════╩═══════╩═════════╝

Answer 2

试试这个。它可以帮助您解决问题。如有任何问题，请告诉我。

SELECT a.typ,
  a.nme,
  MAX(a.int_val),
  MAX(a.str_val)
FROM
  (SELECT 1 AS typ,'doc-1' nme,10 attr,1003 int_val,NULL AS str_val FROM dual
  UNION ALL
  SELECT 1 AS typ,
    'doc-1' nme,
    15 attr,
    NULL int_val,
    'string1' AS str_val
  FROM dual
  UNION ALL
  SELECT 2 AS typ,'doc-2' nme,13 attr,1004 int_val,NULL AS str_val FROM dual
  UNION ALL
  SELECT 2 AS typ,
    'doc-2' nme,
    22 attr,
    NULL int_val,
    'string2' AS str_val
  FROM dual
  UNION ALL
  SELECT 1 AS typ,'doc-3' nme,10 attr,1005 int_val,NULL AS str_val FROM dual
  UNION ALL
  SELECT 1 AS typ,
    'doc-3' nme,
    15 attr,
    NULL int_val,
    'string3' AS str_val
  FROM dual
  )a
GROUP BY a.typ,
  a.nme;

------------------------------OUTPUT----------------------------------
TYP NME MAX(A.INT_VAL)  MAX(A.STR_VAL)
1   doc-3   1005    string3
2   doc-2   1004    string2
1   doc-1   1003    string1
------------------------------OUTPUT----------------------------------

如何在pl-sql

2 个答案: