在Oracle 11g中

Question

移調查詢結果我有一個查詢返回了結果如下表：

 
Element READING1 READING2 READING3 
--------------------------------------- 
1  0.25  1.5  3.5 
2  1.3  2.3  5.5 
3  4.5  5.5  4.3 
..  ..  ..  .. 
n  1.5  2.3  5.5 
--------------------------------------- 

我想在下面的表格輸出：

 
      1  2   3 ..  n 
     --------------------------------------- 
READING1 0.25  1.3  4.5 .. 1.5 
READING2 1.5  2.3  5.5 .. 2.3 
READING3 3.5  5.5  4.3 .. 5.5 

即我要轉表。 我對使用Oracle數據透視用以下方式嘗試：

WITH T AS (
SELECT Element,READING1 from ZZZ; ----(1) 
) 
SELECT * FROM T 
PIVOT(MAX(READING1) FOR ELEMENT IN (1,2,3,..n))  ----(2) 

這給我造成僅供READING1，但我無法產生導致了所有正確的讀數。任何幫助將不勝感激。

由於事先

最好的問候， 注：Kunal

Answer 1

你接近 - 你想要的是UNPIVOT和PIVOT組合：

with T AS (
    select 1 as element, 1.1 as reading1, 1.2 as reading2, 1.3 as reading3 from dual union all 
    select 2 as element, 2.1 as reading1, 2.2 as reading2, 2.3 as reading3 from dual union all 
    select 3 as element, 3.1 as reading1, 3.2 as reading2, 3.3 as reading3 from dual 
) 
select * from (
    select * from t 
    unpivot (reading_value 
    for reading_name in ("READING1", "READING2", "READING3") 
    ) 
    pivot(max(reading_value) for element in (1,2,3) 
) 
) 
order by reading_name 

這個查詢

• 將co lumns reading1，reading2，reading3到單獨行（名字進入reading_name，該值成reading_value）;這爲我們提供了每（元件，reading_name）一行
• 轉換行 1，2 *，3（的值元件）爲列 '1'， '2'， '3';這給了我們每reading_name

UPDATE

一行如果元素列表不知道，直到運行時（例如，因爲用戶有選擇他們的選項），你需要一個更動態的方法。下面是一個解決方案，它爲給定的元素列表動態創建一條SQL語句，並使用sys_refcursor作爲結果集。

-- setup table 
create table T AS 
    select 1 as element, 1.1 as reading1, 1.2 as reading2, 1.3 as reading3 from dual union all 
    select 2 as element, 2.1 as reading1, 2.2 as reading2, 2.3 as reading3 from dual union all 
    select 3 as element, 3.1 as reading1, 3.2 as reading2, 3.3 as reading3 from dual ; 
/

declare 
    l_Elements dbms_sql.Number_Table; 

    function pivot_it(p_Elements in dbms_sql.Number_Table) 
    return sys_refcursor is 
     l_SQL CLOB := empty_clob(); 
     l_Result sys_refcursor; 
    begin 
     l_SQL := ' 
     select * from (
      select * from t 
      unpivot (reading_value 
       for reading_name in ("READING1", "READING2", "READING3") 
      ) 
      pivot(max(reading_value) for element in ('; 
     for i in 1 .. p_Elements.count 
       loop 
        l_SQL := l_SQL || to_char(p_Elements(i)) || ','; 
       end loop; 
     -- remove trailing ','     
     l_SQL := regexp_replace(l_SQL, ',$');     
     l_SQL := l_SQL || ') 
     ) 
    )'; 
     dbms_output.put_line(l_SQL); 
     open l_Result for l_SQL; 
     return l_Result; 
    end;  
begin 
    l_Elements(1) := 1; 
    l_Elements(2) := 2; 
    -- uncomment this line to get all 3 elements 
    -- l_Elements(3) := 3; 
    -- return the cursor into a bind variable (to be used in the host environment) 
    :p_Cursor := pivot_it(l_Elements); 
end; 

你如何使用這個函數返回的遊標取決於您使用的環境 - 在SQL /加你可以直接打印出來，和大多數編程語言甲骨文綁定支持外的the-框。

CAVEAT：儘管此代碼適用於提供的數據，但它甚至缺少基本的錯誤檢查。這一點尤其重要，因爲動態SQL始終是SQL注入攻擊的可能目標。