Using Conditionals... Question (IF statements)

Hello there, I'm rather new to the SQL database scripting but I've had no trouble with basic selects/updates but my main issue right now is that I'm not sure how to use Conditional statements for my current task.

The table I need to get/insert information to is located on a database called

BOS
the table I'm testing the conditional on is
ORDERSOURCES

I want to make an if statement that goes like this

IF "a value of 8888 does not exist" THEN
INSERT INTO ORDERSOURCES
VALUES ('THIS', '8888','THAT')
ELSE
do nothing
END IF

I'm just not sure how to have my if statement point to that
table and check to see if the values 8888 exist(the value name is called code)

I was trying something like
IF @ORDERSOURCES WHERE CODE = '8888' THEN
INSERT

but its not working.

Because in my program as soon as you set the order to not be for internet it removes it from the table so I can't just check for a certain value and then say thats not right and change it. Hopefully you guys aren't as confused as me after reading what I wrote.

Please if you have any insight I would appreciate it so much. Thank you.

I think I need it to iterate thru all the codes and check if the code is there. And if the code isn't there insert it. But I'm just having a hell of a time getting it to select/look for the right values.

Jeez I feel stupid. Ok

IF NOT EXISTS (SELECT * FROM <TABLE> WHERE <VALUE> = 'THIS')

but how do I return text saying "this is already here no worries"

Guess I can just use :

SELECT 'Already existing'