Using key mapping in vi

vi or vim provide a very useful technique whereby user can assign arbitrary functions to control key strokes. For eg, here is one such mapping:

map ^k I/*A*/

When a hits ctrl+k, the line on which the cursor currently is, is commented. To explain the command:
map ^k - assigns the functionality to ctrl+k character
I/*A*/ - concatenation of smaller operations which are
- Move to Esc mode,
I - Insert in the beginning of the line
/* - characters to be inserted
- Move to Esc mode
A - Append at the end of the line
*/ - characters to be appended
- move to Escape mode

The Esc key can be typed by first typing Ctrl+V followed by Esc key.

By adding this mapping to .vimrc file, this mapping can be saved across vim invocations.

Using vi as Line Editor in bash

For folks who are comfortable with vi, use the following command and override the default line editor (emacs) in bash:

$ set -o vi

Now start using vi commands to edit bash commands. It supports both insert and escape modes, just like the vi text editor.

Sorting in a recursive query

Here is a neat utility from Oracle to query a table recursively, and sort results among siblings:

SELECT e.id, e.name, e.manager_id
FROM employee e
START WITH ID = 1
CONNECT BY manager_ID = PRIOR ID
order siblings by e.name;

Note the 'order siblings by' clause. This can be used only with recursive queries and sorts the siblings by the name.