Duel with Dual

Dual is a default table that comes with all Oracle db installations. It is tiny table with just one column and has just one row. See desc below.

desc dual;
DUMMY

select * from dual;
DUMMY
X

It's owner is SYS but all users have access to it. This table always returns one row. So that's something that comes in handy.

Usages:
1. mostly to select pseudo columns from tables or views
2. test any of the Oracle functions

e.g.
select to_date(sysdate) as system_date from dual;
SYSTEM_DATE
6/25/2009

select 'ruchi' as name, 'crazy' as fame from dual;
NAME FAME
ruchi crazy

select upper('ruchi') as ucase from dual;
UCASE
RUCHI

Oracle functions INSTR, SUBSTR, LENGTH, UPPER, LOWER

Usage:
length('snake')
= 5
upper('body')
= BODY
lower('roLLeR')
=roller

subset of a string is substr
substr('thisplace', 5)
= place
substr('thisplace',2,3)
= his

find in a string is instr
instr('thisplace','his')
=2
instr gives this starting position of the searched string in source string.

Toad Shortcuts

F2 - Hide data grid and show full screen editor
F4 - Run desc on the object under the cursor
F6 - Switch between editor and data grid
F7 - Clean editor
F8 - Show SQL statement history
Alt + downArrow - Display last executed SQL statement
Alt + upArrow - Brings previous recalled SQL statement

Ctrl + T or Ctrl + . - to expand Table names

Cmd + Up Arrow: Shortcut to home folder on mac os

Cmd + Down Arrow = Cmd + Enter : Open

Database User Access information

To look up what role/access you have in an Oracle database we can use this query -

select * from dba_role_privs where grantee = 'userid';

Table structure of dba_role_privs:

Column Name    ID    Data Type
GRANTEE         1    VARCHAR2 (30 Byte)  
GRANTED_ROLE    2    VARCHAR2 (30 Byte) -- Roles defined specifically for the db
ADMIN_OPTION    3    VARCHAR2 (3 Byte)  
DEFAULT_ROLE    4    VARCHAR2 (3 Byte)  

If there's no entry for the user-id in this table that means user doesn't have access to the database.

Yesterday I learned to created some basic favicons using GIMP. It was frustrating to begin with but then I figured it out -
1. start with 16x16 px
2. zoom it to upto 800%
3. reduce the brush size to minuscule ...but still it didn't work quite well. However using text works just fine.

I use CVS at work for version control. It's very easy to learn and setup. There are few stumbling blocks though for a new user.

Removing a file permananently from CVS:
rm badfile
cvs remove badfile
* if you decide not to remove the file, just do : cvs update filename cvs commit badfile

Committing without opening editor
cvs commit -m 'interesting msg' filename

The above message format can be used with other cvs commands as well that require a modification message.
e.g
cvs import -m

This tutorial is very helpful and amusing.

An excerpt
1. Two developers, A and B, check out working copies of a project at the same time. The project is at its starting point - no changes have been committed by anyone yet, so all the files are in their original, pristine state.
2. Developer A gets right to work and soon commits her first batch of changes.
3. Meanwhile, developer B watches television.
4. Developer A, hacking away like there's no tomorrow, commits her second batch of changes. Now, the repository's history contains the original files, followed by A's first batch of changes, followed by this set of changes.
5. Meanwhile, developer B plays video games.
6. Suddenly, developer C joins the project and checks out a working copy from the repository. Developer C's copy reflects A's first two sets of changes, because they were already in the repository when C checked out her copy.
7. Developer A, continuing to code as one possessed by spirits, completes and commits her third batch of changes.
8. Finally, blissfully unaware of the recent frenzy of activity, developer B decides it's time to start work. He doesn't bother to update his copy; he just commences editing files, some of which may be files that A has worked in. Shortly thereafter, developer B commits his first changes.