小實驗oracle tcl

Transaction Ctrl Language

savepoint

rollback

savepoint可以理解成一些臨時的書籤記號，執行DDL類語句會摧毀這些書籤。

test1：

SQL> create table t1_ltn (id number);


Table created.


Elapsed: 00:00:00.02
SQL> insert into t1_ltn values (1);


1 row created.


Elapsed: 00:00:00.05
SQL> savepoint a1;


Savepoint created.


Elapsed: 00:00:00.00
SQL> insert into t1_ltn values (2);


1 row created.


Elapsed: 00:00:00.00
SQL> savepoint a2;


Savepoint created.


Elapsed: 00:00:00.00
SQL> commit;


Commit complete.


Elapsed: 00:00:00.02
SQL> rollback to a1;
rollback to a1
*
ERROR at line 1:
ORA-01086: savepoint 'A1' never established in this session or is invalid




Elapsed: 00:00:00.00

一旦commit，savepoint即被破壞。‘

test2：

重複上面的步驟，建立a1，a2兩個savepoint。

此時rollback to a1是成功的，然是隨後rollback to a2會報錯：

SQL> rollback to a1;

Rollback complete.

Elapsed: 00:00:00.00
SQL> rollback to a2;
rollback to a2
*
ERROR at line 1:
ORA-01086: savepoint 'A2' never established in this session or is invalid


Elapsed: 00:00:00.00

但是按照這個邏輯先rollback to a2，再rollbak to a1則是成功的。

說明只能按照savepoint的倒數順序來rollback。