?: (conditional Operator) Problem.

hi
i have this script sample :



Code Snippet
declare @x nvarchar(30)
declare @a nvarchar(30)
set @x = 'Hi'
set @a = (@x ='Hi' ? @x:'GoodBye') -- Error Message

select @a






in line 4, i want to check value of @x variable, if it has 'Hi' value, then pass @x value to @a, otherwise pass 'GoodBye'
to @a. i want to do this checking by ? conditional operator, but sql server give me error :



Code Snippet
Incorrect syntax near '='.





how to solve my problem ?
thanks.