Updating rows a particular empno

Question

Suppose in a table i have to columns EMPNO,AMOUNT----along with each empno thr are 10 values present
by mistake i executed these query and all the values got converted to zero
SQL>update emp set amount=0 where empno='2492';
but before executing this query i made a note of all the 10 values ..
I want to insert back the old values into all the 10 rownum that have been converted to zero against that empno in the amount column
can any1 help me out how to do this ....

Answer 1

In that EMPNO IS primary key. So only one row will be available :) . Try this way.
SQL> create table EMP_TEST
  2  (
  3    EMPNO  NUMBER,
  4    AMOUNT NUMBER
  5  );
Table created.
SQL> INSERT INTO EMP_TEST VALUES(1234,NULL);
1 row created.
SQL> /
1 row created.
SQL> /
1 row created.
SQL> commit;
Commit complete.
SQL> select * from emp_test;
     EMPNO     AMOUNT
      1234
      1234
      1234
SQL> UPDATE EMP_TEST
  2    SET AMOUNT=&AMT
  3    WHERE ROWID=(
  4                  SELECT ROWID FROM
  5                (SELECT ROWID,EMPNO,AMOUNT,ROW_NUMBER() OVER (ORDER BY EMPNO) rn
  6                     FROM EMP_TEST
  7                     WHERE EMPNO=1234
  8                     )
  9                 WHERE rn=&rownumber
10                );
Enter value for amt: 200
old   2:   SET AMOUNT=&AMT
new   2:   SET AMOUNT=200
Enter value for rownumber: 1
old   9:                WHERE rn=&rownumber
new   9:                WHERE rn=1
1 row updated.
SQL> /
Enter value for amt: 300
old   2:   SET AMOUNT=&AMT
new   2:   SET AMOUNT=300
Enter value for rownumber: 3
old   9:                WHERE rn=&rownumber
new   9:                WHERE rn=3
1 row updated.
SQL> select * from emp_test;
     EMPNO     AMOUNT
      1234        200
      1234
      1234        300
SQL>