how to check if var empty

[Vincent]

hello,

how can i check if a variable is empty?

 

my code(not all):

query_sql "SELECT `last_mac` FROM `login` WHERE `char_id` = " + getcharid(0) + "", .@lastmac;

the fild "last_mac" can be empty because of this

COLUMN `last_mac` VARCHAR(18) NOT NULL DEFAULT ''

 But how can i check this with a if? This dont work

if (.@lastmac == )
{
bla bla
}

Edited December 28, 2013 by Vincent

[Emistry]

your script will end up failed...

1. variable is not saved as string
2. login table dont have char_id column

it should be like this

query_sql( "SELECT `last_mac` FROM `login` WHERE `account_id` = "+getcharid(3), .@lastmac$ );

then to check if the MAC address is empty or not..

if( .@lastmac$[.@i] == "" ){
   // mac address is empty
}

[klesler]

So 

 if (!.var)

means 'if var is empty' ?

If I want it to be true if not empty, should i only use :

if (.var)

Or should I use

if (!(!.var))

?

 

I was afraid that !.var would only check if .var exists, not validate its value.

Edited April 19, 2018 by klesler

[PewN]

if(!.@lastmac )

[Vincent]

Thanks both