请教一个SQL语句

tomorrow_mornin

请问如何删除一张表里的重复行？在线等

IBMSAN

SQL>; create table test (col1 number(4),memo varchar2(10));

Table created.

SQL>; select * from test;

no rows selected

SQL>; insert into test values (1,'aaa');

1 row created.

SQL>; insert into test values (1,'aaa');

1 row created.

SQL>; insert into test values (2,'bbb');

1 row created.

SQL>; insert into test values (3,'ccc');

1 row created.

SQL>; insert into test values (4,'ddd');

1 row created.

SQL>; insert into test values (2,'bbb');

1 row created.

SQL>; commit;

Commit complete.

SQL>; select * from test;

      COL1 MEMO
---------- ----------
         1 aaa
         1 aaa
         2 bbb
         3 ccc
         4 ddd
         2 bbb

6 rows selected.

SQL>; select col1,memo from test A where A.rowid = (select max(B.rowid) from test B where A.col1 = B.col1 and A.memo = B.memo);

      COL1 MEMO
---------- ----------
         1 aaa
         3 ccc
         4 ddd
         2 bbb

SQL>; select col1,memo from test A where A.rowid != (select max(B.rowid) from test B where A.col1 = B.col1 and A.memo = B.memo);

      COL1 MEMO
---------- ----------
         1 aaa
         2 bbb

SQL>; delete from test A where A.rowid != (select max(B.rowid) from test B where A.col1 = B.col1 and A.memo = B.memo);

2 rows deleted.

SQL>; select * from test;

      COL1 MEMO
---------- ----------
         1 aaa
         3 ccc
         4 ddd
         2 bbb

SQL>; commit;

Commit complete.

SQL>;

tomorrow_mornin

谢谢楼上的兄弟，很详细的解答！