Oracle使用SQL實現矩陣轉置

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中，很容易實現的，但很多人都不知道怎么用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1：表1轉置成表2

 

--1.添加測試數據
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;

--2.SQL實現
--方法1：unpivot+pivot (適用於oracle11g或以上)
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2: max+decode
select col, 
       max(decode(rn, 1, v)), 
       max(decode(rn, 2, v)), 
       max(decode(rn, 3, v)),
       max(decode(rn, 4, v)), 
       max(decode(rn, 5, v))
 from (select t.rn, 
              decode(t1.lv, 1, 'A', 2, 'B') as col,
              decode(t1.lv, 1, a, 2, b) v
         from (select row_number() over(order by a, b) as rn, a, b
                 from tmp
              ) t,
             (select level lv from dual connect by level <= 2) t1
       )
group by col;

--方法3: model子句 (適用於oracle10g或以上)
select decode(rn, 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 rn)
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])
);

  需求2：表2轉置成表1

  

--1.添加測試數據
create table tmp1 as 
select 'A' AS COL,'A1' AS V1,'A2' AS V2,'A3' AS V3,'A4' AS V4,'A5' AS V5 from dual
union all
select 'B','B1','B2','B3','B4','B5' from dual;

--2.SQL實現
--方法1: unpivot+pivot (適用於oracle11g或以上)  上面的方法反過來用
select a, b
  from (select *
          from tmp1 
        unpivot(v for col1 in(v1, v2, v3, v4, v5))
        )
  pivot(max(v) for col in('A' as a, 'B' as b))
order by a, b;

--方法2：max+decode
select max(decode(col, 'A', v)) as a, max(decode(col, 'B', v)) as b
 from (select col, lv, decode(lv, 1, v1, 2, v2, 3, v3, 4, v4, 5, v5) as v
         from tmp1,
              (select level as lv from dual connect by level <= 5)
      )
 order by a, b;

--方法3：model子句 (適用於oracle10g或以上)
select a, b
  from tmp1
 model
return updated rows
dimension by(row_number()over(order by col) as r)
measures (v1,v2,v3,v4,v5,v1 as a,v2 as b)
rules iterate(5)
(
A[ITERATION_NUMBER+1]=DECODE(CV(R),1,V1[1],2,V2[1],3,V3[1],4,V4[1],V5[1]),
B[ITERATION_NUMBER+1]=DECODE(CV(R),1,V1[2],2,V2[2],3,V3[2],4,V4[2],V5[2])
);