Seems an odd requirement, and the wrong place to do it as Lutz mentions.

Nevertheless...

DECLARE @demo

TABLE (

data DECIMAL(5,2) NOT NULL,

odd_format AS

CASE SIGN(data)

WHEN -1 THEN CONVERT(VARCHAR(7), data)

-- Assumes zero is 'positive'

ELSE '+' + CONVERT(VARCHAR(7), data)

END

PERSISTED NOT NULL

);

INSERT @demo (data)

SELECT TOP (20)

CHECKSUM(NEWID()) % 99999 / 100.0

FROM master.sys.all_columns;

SELECT *

FROM @demo;

Paul