Oracle humor:  Hidden table names Oracle Tips by Tony Jambu

 

Oracle guru Tony Jambu published this great trick for the DBA. 

Try this code out on your DBA and see how long he or she takes to figure it out.

First, create a fairly large table with a specially formulated name ?^HDROPME.

Then, ask your DBA to drop the table called ?DROPME? and time how long he or she takes.

To create table:

CREATE TABLE ?HDROPME?

(co1 number)

STORAGE (INITIAL 100m) ;

Notice the two additional characters in front of ?DROPME?? This is a space??

Followed by the Backspace or CHR (8) character.(In vi, you would type ?CTRL-v? followed by the Backspace character)

SELECT TABLE_NAME FROM USER_TABELS;

 

TABLE_NAME

---------------------

xDROPME

Understanding why-the CHR(8) or backspace character will behave is if you had typed the Backspace key, erase the previous character, In this case the single space. The following sample code will provide a visual explanation.

create table  ?ABC - (co1 number);

create table ?ABC^H? (co1 number);

create table ?ABC^H^H? (co1 number);

create table ?ABC^H ^H ^H? (co1 number);

create table ?HABC? (co1 number);

 

select table-name, table-name//?- - ?

 

 

TABLE_NAME                    TABLE_NAME

 

ABC                           ABC - -

AB                            AB- -

A                             A--

                              - - C

ABC                           ABC - -                                          

 

5 rows selected.

The ?^H character is the backspace character and will shift the cursor back by one space.

The sequence ?A^HB? will produce the following string, ?B? on terminals/screens that display plain ASCII characters, this is because after the character ?A? is drawn, the ?^H? character will backspace over ?A? and ?B? is drawn over it.

 

 

If you like Oracle tuning, you might enjoy my book "Oracle Tuning: The Definitive Reference", with 950 pages of tuning tips and scripts.  You can buy it direct from the publisher for 30%-off and get instant access to the code depot of Oracle tuning scripts.