前不久，同事问了我一个这样的问题，并且附上了实验记录，在oracle中，为何shudown abort后导致了事务的提交，而并非回滚？现将他的实验记录贴出来，细心的朋友可能会马上发现问题。
SQL> conn scott/scott
Connected.
SQL> set line 100 pagesize 200
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ----------------- ---------- ---------- ----------
7369 SMITH CLERK 7902 19801217 00:00:00 800 20
7499 ALLEN SALESMAN 7698 19810220 00:00:00 1600 300 30
7521 WARD SALESMAN 7698 19810222 00:00:00 1250 500 30
7566 JONES MANAGER 7839 19810402 00:00:00 2975 20
7654 MARTIN SALESMAN 7698 19810928 00:00:00 1250 1400 30
7698 BLAKE MANAGER 7839 19810501 00:00:00 2850 30
7782 CLARK MANAGER 7839 19810609 00:00:00 2450 10
7788 SCOTT ANALYST 7566 19870419 00:00:00 3000 20
7839 KING PRESIDENT 19811117 00:00:00 5000 10
7844 TURNER SALESMAN 7698 19810908 00:00:00 1500 0 30
7876 ADAMS CLERK 7788 19870523 00:00:00 1100 20
7900 JAMES CLERK 7698 19811203 00:00:00 950 30
7902 FORD ANALYST 7566 19811203 00:00:00 3000 20
7934 MILLER CLERK 7782 19820123 00:00:00 1300 10
14 rows selected.
SQL> delete from emp where comm is not null;
4 rows deleted.
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ----------------- ---------- ---------- ----------
7369 SMITH CLERK 7902 19801217 00:00:00 800 20
7566 JONES MANAGER 7839 19810402 00:00:00 2975 20
7698 BLAKE MANAGER 7839 19810501 00:00:00 2850 30
7782 CLARK MANAGER 7839 19810609 00:00:00 2450 10
7788 SCOTT ANALYST 7566 19870419 00:00:00 3000 20
7839 KING PRESIDENT 19811117 00:00:00 5000 10
7876 ADAMS CLERK 7788 19870523 00:00:00 1100 20
7900 JAMES CLERK 7698 19811203 00:00:00 950 30
7902 FORD ANALYST 7566 19811203 00:00:00 3000 20
7934 MILLER CLERK 7782 19820123 00:00:00 1300 10
10 rows selected.
SQL> shutdown abort;
ORA-01031: insufficient privileges
SQL> conn / as sysdba
Connected.
SQL> shutdown abort
ORACLE instance shut down.
SQL> startup;
ORACLE instance started.
Total System Global Area 1.3495E+11 bytes
Fixed Size 2270072 bytes
Variable Size 3.6776E+10 bytes
Database Buffers 9.7979E+10 bytes
Redo Buffers 197844992 bytes
Database mounted.
Database opened.
SQL> conn scott/scott
Connected.
SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- ----------------- ---------- ---------- ----------
7369 SMITH CLERK 7902 19801217 00:00:00 800 20
7566 JONES MANAGER 7839 19810402 00:00:00 2975 20
7698 BLAKE MANAGER 7839 19810501 00:00:00 2850 30
7782 CLARK MANAGER 7839 19810609 00:00:00 2450 10
7788 SCOTT ANALYST 7566 19870419 00:00:00 3000 20
7839 KING PRESIDENT 19811117 00:00:00 5000 10
7876 ADAMS CLERK 7788 19870523 00:00:00 1100 20
7900 JAMES CLERK 7698 19811203 00:00:00 950 30
7902 FORD ANALYST 7566 19811203 00:00:00 3000 20
7934 MILLER CLERK 7782 19820123 00:00:00 1300 10
10 rows selected.
同事前来问我，为何重启后，事务提交了？不是应该回滚的么？细心的同学可能已经发现了问题，执行完事务后，会话进行shutdown abort失败（权限不足），使用了conn 命令进行了用户的切换，引用Oracle官方文档中的描述”：
Usage
CONNECT commits the current transaction to the database, disconnects the current username from Oracle Database, and reconnects with the specified username.
这个问题虽然看起来过于细节也很基础，但是稍不注意便会造成数据的隐式COMMIT，特别是在SQLPLUS中操作数据的过程中，需要特别小心。