Oracle LISTAGG排重方法

1.使用正则表达式进行排重

SELECT regexp_replace('2,2,3,4,5 ', '([^,]+)(,\1)+', '\1') AS col
  FROM dual

查询结果：

SQL> SELECT regexp_replace('2,2,3,4,5 ', '([^,]+)(,\1)+', '\1') AS col
  2    FROM dual
  3  ;
 
COL
--------
2,3,4,5

可以对字符串进行排重

2. 使用上面的正则表达式对listagg进行排重

SELECT listagg(t.deptno, ',') within GROUP(ORDER BY t.deptno) deptno,
       regexp_replace((listagg(t.deptno, ',') within GROUP(ORDER BY t.deptno)), '([^,]+)(,\1)+', '\1') bl_number
  FROM scott.emp t

执行结果：

SQL> SELECT listagg(t.deptno, ',') within GROUP(ORDER BY t.deptno) deptno,
  2         regexp_replace((listagg(t.deptno, ',') within GROUP(ORDER BY t.deptno)), '([^,]+)(,\1)+', '\1') bl_number
  3    FROM scott.emp t
  4  ;
 
DEPTNO                                                                           BL_NUMBER
-------------------------------------------------------------------------------- --------------------------------------------------------------------------------
10,10,10,20,20,20,20,20,30,30,30,30,30,30                                        10,20,30

成功对listagg排重。