Is it safe to do a TO_NUMBER(TO_CHAR(:n)) ?
var n number
exec :n := 9.9999999999999999999999999999999999e125
select to_number(to_char(:n)) from dual;
ORA-01722: invalid number
If a positive NUMBER value is extremely large and cannot be represented in the specified format, then the infinity sign (~) replaces the value
select to_char(:n) from dual;
I wrote more about infinity here
When and how do you commit a transaction?
SQL> insert into lsc_t(x) values(1); ... (1) not committed
SQL> commit; ... (1) committed
SQL> insert into lsc_t(x) values(2); ... (2) not committed
SQL> alter table lsc_t disable primary key; ... (2) committed
SQL> set autocommit ON
SQL> insert into lsc_t(x) values(3); ... (3) committed
SQL> set autocommit OFF
SQL> insert into lsc_t(x) values(4); ... (4) not committed
SQL> disc ... (4) committed
Row 1 is committed after the commit keyword.
Row 2 is implicitely committed
after before the alter table ddl statement.
Row 3 is autocommitted. Autocommit exists in sqlplus, but is more often seen in stateless applications (for instance a web application).
Row 4 is committed after a successfull disconnection.
But what appends if you kill your current session?
SQL> insert into lsc_t(x) values (5);
1 row created.
PID TTY TIME CMD
13903 pts/33 0:00 ksh
22384 pts/33 0:00 sqlplus
SQL> !kill 22384
The row 5 is not commited
Ref: Overview of Transaction Management
A transaction ends when any of the following occurs:
– A user issues a COMMIT or ROLLBACK statement without a SAVEPOINT clause.
– A user runs a DDL statement such as CREATE, DROP, RENAME, or ALTER (*).
If the current transaction contains any DML statements, Oracle Database
first commits the transaction, and then runs and commits the DDL statement
as a new, single statement transaction.
– A user disconnects from Oracle Database. The current transaction is committed.
– A user process terminates abnormally. The current transaction is rolled back.
(*) but not ALTER SESSION …
Please read On Implicit Commit