select '000'+CONVERT(varchar(10),999)+'00' , CONVERT(varchar(19),GETDATE(),120)
select '000'+CONVERT( char(10),999)+'00' , CONVERT(varchar(6),GETDATE(),12)
select '000'+STR(199.08,10,4), CONVERT(varchar(8),GETDATE(),112)
00099900 2019-12-07 16:22:04
000999 00 191207
000 199.0800 20191207