how to define global variable use in whole site?

[eluser]Unknown[/eluser]
in the query i want to give table name from global array for use in whole site.

[eluser]Abdul Malik Ikhsan[/eluser]

Code:

$ci = & get_instance();
$ci->var = 'value';

[eluser]Unknown[/eluser]
from where i can define it i mean which file config.php or anywhere ?

[eluser]PhilTem[/eluser]
I'd suggest you put these kind of things in constants defined in ./application/config/constants.php so you can access them side wide.