T-SQL, String split

CREATE FUNCTION split
(
        @string nvarchar(4000),
        @delimiter char(1)
)
RETURNS
@splitted TABLE
(
        Value nvarchar(4000)
)
AS
BEGIN
        DECLARE @a SMALLINT
        DECLARE @b SMALLINT
        SET @a = charindex(@delimiter, @string)
        INSERT @splitted VALUES (substring(@string, 1, @a-1))
        WHILE @a <> 0
        BEGIN
                SET @b = charindex(@delimiter, @string, @a+1)
                IF @b <> 0
                        INSERT @splitted VALUES (substring(@string, @a+1, @b-@a-1))
                ELSE
                        INSERT @splitted VALUES (substring(@string, @a+1, len(@string)-@a))
                SET @a = @b
        END
        RETURN
END