Deduplication query:
| SQL> select * from flash_tbl;
ID VL ---------- -- 10 I 11 J 12 K 13 L 14 M 15 N 16 O 17 P 18 Q 19 R 20 S
ID VL ---------- -- 1 / 2 A 3 B 4 C 5 D 6 E 7 F 8 G 9 H 1 / 2 A
ID VL ---------- -- 3 B 4 C 5 D 6 E 7 F 8 G 9 H 1 / 2 A 3 B 4 C
ID VL ---------- -- 5 D 6 E 7 F 8 G 9 H
38 rows selected. SQL> select distinct id,vl from flash_tbl; ID VL ---------- -- 11 J 14 M 7 F 8 G 20 S 4 C 5 D 12 K 16 O 17 P 1 /
ID VL ---------- -- 10 I 13 L 2 A 3 B 15 N 18 Q 6 E 9 H 19 R 20 rows selected. |
Delete duplicate data (two ways)
| SQL> select * from flash_tbl a where rowid != (select max(rowid) from flash_tbl b where a.id=b.id); ----- find duplicate data SQL> delete from flash_tbl a where rowid != (select max(rowid) from flash_tbl b where a.id=b.id); ----- delete duplicate data ----------------------------------------------------------------------------------------------------------------------------------- SQL> select * from flash_tbl where Id in (select Id from flash_tbl group by Id having count(Id) > 1); -----查出重复数据 SQL> delete from flash_tbl where Id in (select Id from flash_tbl group by Id having count(Id) > 1) and rowid not in (select min(rowid) from flash_tbl group by Id having count(Id)>1); -----删掉重复数据 ------------------------------------------------------------------------------------------------------------------------------------ |