Perl note

What are the basic SQL*Plus commands?

The following SQL*Plus commands are available:

ACCEPT	Get input from the user
DEFINE	Declare a variable (short: DEF)
DESCRIBE	Lists the attributes of tables and other objects (short: DESC)
EDIT	Places you in an editor so you can edit a SQL command (short: ED)
EXIT or QUIT	Disconnect from the database and terminate SQL*Plus
GET	Retrieves a SQL file and places it into the SQL buffer
HOST	Issue an operating system command (short: !)
LIST	Displays the last command executed/ command in the SQL buffer (short: L)
PROMPT	Display a text string on the screen. Eg prompt Hello World!!!
RUN	List and Run the command stored in the SQL buffer (short: /)
SAVE	Saves command in the SQL buffer to a file. Eg "save x" will create a script file called x.sql
SET	Modify the SQL*Plus environment eg. SET PAGESIZE 23
SHOW	Show environment settings (short: SHO). Eg SHOW ALL, SHO PAGESIZE etc.
SPOOL	Send output to a file. Eg "spool x" will save STDOUT to a file called x.lst
START	Run a SQL script file (short: @)

Popups in Javascript

Sometimes it's useful to add a popup to your pages. When the user clicks on a link, a new window opens and displays a page.

There are two ways to do this. You can add a TARGET="_blank" to the -tag, but this simply opens a new browser window that completely obscures the old one.

This may be what you want, but at other times a small window on top of the large browser window is much better. This small window is popularly known as a popup.

First the basic syntax of how to create a popup, then an explanation of the script, including a table of the most common arguments you can give to a popup and the problem of focusing.
Then a new way of adding popup behaviour to a link. This site uses the new system because it's much cleaner than the old one.
Finally some notes about writing content directly into the popup. This gives several problems, most importantly the confusion over exactly what the URL of the popup is.

This page only treats the opening of popups. For communication between the opening window and the popup, see the Cross-window scripting page.

Creating a popup

To create a popup you'll need the following script:

Then, you link to it by:

Link to popup

Open popup.

See below for a far cleaner way of adding popup behaviour to a link.

Explanation

First, you open the new window. The page to be opened is passed on by the argument url. Note that, if you want to open a page on another server, Explorer will frequently give errors. This is a feature, not a bug, so there's little you can do about it.

You have to give a name to the window (in this case, name). However, this name is completely useless.

In addition, you have to load the window into a JavaScript variable. The reasons for this are complex and have mostly to do with preventing errors in various browsers, especially when you want more links to lead to the same popup.

function popitup(url) {
 newwindow=window.open(url,'name','height=200,width=150');

Arguments

So first we define the url to be loaded in the popup and then the useless name.

As third argument, you can assign all kinds of variables. Most common are height and width, which define the height and width of the new window.

'height=200,width=150'

As soon as you define anything, all yes | no arguments that you have not defined are set to no.
Warning: Spaces or hard returns are not allowed within the quote-marks.

Open popup, and set the arguments through the checkboxes below.

Selecting and deleting duplicate rows postgresql

create table test ( a text, b text );
-- unique values
insert into test values ( 'x', 'y');
insert into test values ( 'x', 'x');
insert into test values ( 'y', 'y' );
insert into test values ( 'y', 'x' );
-- duplicate values
insert into test values ( 'x', 'y');
insert into test values ( 'x', 'x');
insert into test values ( 'y', 'y' );
insert into test values ( 'y', 'x' );
-- one more double duplicate
insert into test values ( 'x', 'y');
--
select oid, a, b from test;
--
-- select duplicate rows
--
select o.oid, o.a, o.b from test o
where exists ( select 'x'
from test i
where i.a = o.a
and i.b = o.b
and i.oid < o.oid
);
--
-- delete duplicate rows
--
-- Note: PostgreSQL dosn't support aliases on
-- the table mentioned in the from clause
-- of a delete.
--

delete from test
where exists ( select 'x'
from test i
where i.a = test.a
and i.b = test.b
and i.oid < test.oid
);
--
-- Let's see if it worked.
--

select oid, a, b from test;

--
-- Delete duplicates with respect to a only, ignoring
-- the value in b. Note, the first deletion leaves the
-- first oid with the unique values and removes subsequent
-- ones, in this delete we reverse the direction of the <
-- to save the last oid, and remove the previous ones.
--

delete from test
where exists ( select 'x'
from test i
where i.a = test.a
and i.oid > test.oid
);

--
-- Let's see if it worked.
--

select oid, a, b from test;

Moving, renaming, and copying files in UNIX


cp file1 file2          copy a file
mv file1 newname        move or rename a file
mv file1 ~/AAA/         move file1 into sub-directory AAA in your home directory.
rm file1 [file2 ...]    remove or delete a file
rm -r dir1 [dir2...]    recursivly remove a directory and its contents BE CAREFUL!
mkdir dir1 [dir2...]    create directories
mkdir -p dirpath        create the directory dirpath, including all implied directories in the path.
rmdir dir1 [dir2...]    remove an empty directory

Changing file permissions and attributes in UNIX

chmod 755 file       Changes the permissions of file to be rwx for the owner, and rx for
                    the group and the world. (7 = rwx = 111 binary. 5 = r-x = 101 binary)
chgrp user file      Makes file belong to the group user.
chown cliff file     Makes cliff the owner of file.
chown -R cliff dir   Makes cliff the owner of dir and everything in its directory tree.

You must be the owner of the file/directory or be root before you can do any of these things.

Listing directory contents in UNIX

ls    list a directory
ls -l    list a directory in long ( detailed ) format

  for example:
$ ls -l
drwxr-xr-x    4 cliff    user        1024 Jun 18 09:40 WAITRON_EARNINGS
-rw-r--r--    1 cliff    user      767392 Jun  6 14:28 scanlib.tar.gz
^ ^  ^  ^     ^   ^       ^           ^      ^    ^      ^
| |  |  |     |   |       |           |      |    |      | 
| |  |  |     | owner   group       size   date  time    name
| |  |  |     number of links to file or directory contents
| |  |  permissions for world
| |  permissions for members of group
| permissions for owner of file: r = read, w = write, x = execute -=no permission
type of file: - = normal file, d=directory, l = symbolic link, and others...

ls -a        List the current directory including hidden files. Hidden files start
            with "."
ls -ld *     List all the file and directory names in the current directory using
            long format. Without the "d" option, ls would list the contents
            of any sub-directory of the current. With the "d" option, ls
            just lists them like regular files.

Basics of the vi editor

Opening a file
vi filename

               Creating text
Edit modes: These keys enter editing modes and type in the text
of your document.

i     Insert before current cursor position
I     Insert at beginning of current line
a     Insert (append) after current cursor position
A     Append to end of line
r     Replace 1 character
R     Replace mode
 Terminate insertion or overwrite mode

                Deletion of text

x     Delete single character
dd    Delete current line and put in buffer
ndd   Delete n lines (n is a number) and put them in buffer
J     Attaches the next line to the end of the current line (deletes carriage return).

                Oops

u     Undo last command

                cut and paste
yy    Yank current line into buffer
nyy   Yank n lines into buffer
p     Put the contents of the buffer after the current line
P     Put the contents of the buffer before the current line

               cursor positioning
^d    Page down
^u    Page up
:n    Position cursor at line n
:$    Position cursor at end of file
^g    Display current line number
h,j,k,l Left,Down,Up, and Right respectivly. Your arrow keys should also work if
     if your keyboard mappings are anywhere near sane.

              string substitution

:n1,n2:s/string1/string2/[g]       Substitute string2 for string1 on lines
                                  n1 to n2. If g is included (meaning global), 
                                  all instances of string1 on each line
                                  are substituted. If g is not included,
                                  only the first instance per matching line is
                                  substituted.

   ^ matches start of line
   . matches any single character
   $ matches end of line

These and other "special characters" (like the forward slash) can be "escaped" with \
i.e to match the string "/usr/STRIM100/SOFT" say "\/usr\/STRIM100\/SOFT"

Examples:

:1,$:s/dog/cat/g                   Substitute 'cat' for 'dog', every instance
                                  for the entire file - lines 1 to $ (end of file)

:23,25:/frog/bird/                 Substitute 'bird' for 'frog' on lines
                                  23 through 25. Only the first instance
                                  on each line is substituted.


             Saving and quitting and other "ex" commands

These commands are all prefixed by pressing colon (:) and then entered in the lower
left corner of the window. They are called "ex" commands because they are commands
of the ex text editor - the precursor line editor to the screen editor
vi.   You cannot enter an "ex" command when you are in an edit mode (typing text onto the screen)
Press  to exit from an editing mode.

:w                Write the current file.
:w new.file       Write the file to the name 'new.file'.
:w! existing.file Overwrite an existing file with the file currently being edited.
:wq               Write the file and quit.
:q                Quit.
:q!               Quit with no changes.

:e filename       Open the file 'filename' for editing.

:set number       Turns on line numbering
:set nonumber     Turns off line numbering