行列转换的另一种

将表中的字符串值分隔成多个字符串，其中以逗号作为分隔符。

create table t1 (col1 number, col2 varchar2(200));

insert into t1 values (1,'table,chairs,cushion,sofa');
insert into t1 values (2,'tea,coffee,milk,sugar');
commit;

 

SELECT keyvalue, substr(p.mystring, p.pos1, p.pos2 - p.pos1) element
  FROM (SELECT keyvalue,
               instr(t.mystring, ',', 1, o.pos) + 1 pos1,
               decode(instr(t.mystring, ',', 1, o.pos + 1),
                      0,
                      length(t.mystring) + 1,
                      instr(t.mystring, ',', 1, o.pos + 1)) pos2,
               lower(t.mystring) AS mystring
          FROM (SELECT col1 AS keyvalue, col2 AS mystring FROM t1) t,
               (SELECT LEVEL AS pos FROM dual CONNECT BY LEVEL < 100) o
         WHERE instr(t.mystring, ',', 1, o.pos) > 0) p
 ORDER BY keyvalue, p.pos1;

---------------------

1     1     chairs

2     1     cushion

3     1     sofa

4     2     coffee

5     2     milk

6     2     sugar