csm.dba's blog

What data type should I use: CHAR or VARCHAR2???



We all know that CHAR and VARCHAR2 are two different datatypes used for storing strings in Oracle. When I asked many people about what’s the difference exactly, all were saying VARCHAR2 can be used for variable sized character strings. As I’m not satesfied with the answer, as always, I’ve decided to do my own experiments on these two. Please find the exercise I’ve performed below.

SQL> create table t1 (col1 char(10), col2 varchar2(10));

Table created.

SQL> insert into t1 values(‘Oracle’,'Oracle’);

1 row created.

“ORA-01081: cannot start already-running ORACLE” While creating a new Database


Hi Geeks,

When I was doing a research on Oracle Database creation, through DBCA, last week, I came across a very interesting scenario which I couldn’t stop sharing with you :)

I have a cluster of machines (don’t confuse it with a RAC cluster but just a group of machines required for my application deployment) with installed and a Database instance running.

I got a requirement to remove everything accumulated in the machine as a result of the Oracle installation and the Database creation: The installation directories, the datafiles, oratab entries etc…

Can you create objects in a READ ONLY tablespace?

Hi Oracle geeks,

Last Friday, I’ve noticed a strange thing happening in my Database: I’m able to create objects in a tablespace which is marked READ ONLY !!!

Don’t believe this?? See the below

SQL> create tablespace ro datafile ‘/xxx/RO.DBF’ size 10M AUTOEXTEND ON;
Tablespace created.

SQL> alter tablespace ro read only;
Tablespace altered.

SQL> select status from dba_tablespaces where tablespace_name=’RO’;

SQL> sho user

Subscribe to RSS - csm.dba's blog