Oracle listparts deduplication method, oraclelistparts deduplication

Oracle listparts deduplication method, oraclelistparts deduplication
1. Use a regular expression to remove duplicates

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

Query results:

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

You can sort strings by weight.

2. Use the regular expression above to weight the listparts.

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

Execution result:

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

The listparts is reordered successfully.