convert bigint to nvarchar by format

Question

How can I convert bigint to nvarchar using the following scheme:

• 1 converts to 0001
• 123 converts to 0123

Answer 1

Here a possible solution:

declare @i bigint
SET @i = 125
select right( '0000' + ltrim( str( @i ) ), 4 )

Answer 2

Slight variation of danihp's, but using the REPLICATE function.

DECLARE @aVar bigint
SELECT @aVar = 123;
SELECT RIGHT(REPLICATE('0', 4) + LTRIM(STR(@aVar)), 4)

Will return 0123