在使用數據庫使用報表時，往往會遇到矩陣轉置。這個需求在Excel是很容易實現的，但很多人都不知道怎麽用Oracle數據庫實現，下面給大家展示幾種使用SQL實現的方法。

需求：表1轉置成表2

測試數據:

CREATE TABLE TMP AS 
SELECT ‘A1‘ AS A, ‘B1‘ AS B
FROM   DUAL
UNION ALL
SELECT ‘A2‘ AS A, ‘B2‘ AS B
FROM   DUAL
UNION ALL
SELECT ‘A3‘ AS A, ‘B3‘ AS B
FROM   DUAL
UNION ALL
SELECT ‘A4‘ AS A, ‘B4‘ AS B
 
FROM   DUAL
UNION ALL
SELECT ‘A5‘ AS A, ‘B5‘ AS B
FROM   DUAL

方法一：UNPIVOT+PIVOT 數據庫11g以上

SELECT *
FROM   (SELECT R, COL, V
         FROM   (SELECT ROW_NUMBER() OVER(ORDER BY A, B) AS R, A, B
                  FROM   TMP) UNPIVOT(V FOR COL IN(A, B)))
PIVOT (MAX(V) FOR R IN(1, 2, 3, 4, 5));

方法二: MAX+DECODE

SELECT COL, MAX(DECODE(R, 1, V)), MAX(DECODE(R, 2, V)), MAX(DECODE(R, 3, V)),
       MAX(DECODE(R, 4, V)), MAX(DECODE(R, 5, V))
FROM   (SELECT T.R, DECODE(T1.L, 1, ‘A‘, 2, ‘B‘) AS COL,
                DECODE(T1.L, 1, A, 2, B) V
         FROM   (SELECT ROW_NUMBER() OVER(ORDER BY A, B) AS R, A, B
                  
 
FROM   TMP) T,
                (SELECT LEVEL L
                  FROM   DUAL
                  CONNECT BY LEVEL <= 2) T1)
GROUP  BY COL

方法三:MODEL子句 數據庫10g以上

SELECT DECODE(R, 1, ‘A‘, ‘B‘) AS COL, V1, V2, V3, V4, V5
FROM   TMP
MODEL
RETURN UPDATED ROWS
DIMENSION BY(ROW_NUMBER()OVER(ORDER BY A,B) AS R)
MEASURES (A,B,A AS V1,A AS V2,A AS V3,A AS V4,A AS V5)
RULES
(
V1[R<=2]=DECODE(CV(R),1,A[1],2,B[1]), 
V2[R<=2]=DECODE(CV(R),1,A[2],2,B[2]), 
V3[R<=2]=DECODE(CV(R),1,A[3],2,B[3]), 
V4[R<=2]=DECODE(CV(R),1,A[4],2,B[4]), 
V5[R<=2]=DECODE(CV(R),1,A[5],2,B[5])
)

Oracle使用SQL實現矩陣轉置