ORACLE行專列轉換

一、採用SQL decode和PL/SQL函數實現
1、固定列數的行列轉換
如

student subject grade
---------------------------
student1 語文 80
student1 數學 70
student1 英語 60
student2 語文 90
student2 數學 80
student2 英語 100
……
轉換爲 
語文 數學 英語
student1 80 70 60
student2 90 80 100
……
語句如下：
select student,sum(decode(subject,'語文', grade,null)) "語文",
sum(decode(subject,'數學', grade,null)) "數學",
sum(decode(subject,'英語', grade,null)) "英語"
from table
group by student

2、動態的行列轉換需要通過存儲過程拼接sql語句

如：

CREATE OR REPLACE PROCEDURE GET_INSPECT_ITEM
(
    P_INSPECT_ID        IN VARCHAR2
    ,Re_CURSOR           OUT SYS_REFCURSOR 
)
AS
  SQLSTR VARCHAR2 (4000);
BEGIN
   DECLARE
   CURSOR C_CURSOR
   IS
   SELECT DISTINCT QCITEM_NAME
     FROM REP_INSPECT_ITEM
      WHERE INSPECT_ID=P_INSPECT_ID;
    c_row C_CURSOR %ROWTYPE;
    BEGIN
             SQLSTR:='SELECT INSPECT_ID,SAMPLE_ID';
              FOR c_row IN C_CURSOR LOOP
              SQLSTR:=SQLSTR||', MAX(DECODE(T.QCITEM_NAME,''' ||c_row.QCITEM_NAME||''',T.VALUE,null)) AS "' || c_row.QCITEM_NAME || '"';
              END LOOP;
              SQLSTR:=SQLSTR||'FROM REP_INSPECT_ITEM T GROUP BY SAMPLE_ID,INSPECT_ID HAVING INSPECT_ID='||P_INSPECT_ID;
              OPEN Re_CURSOR FOR SQLSTR ;
   END;
END GET_INSPECT_ITEM;

結果如下圖：