DECLARE @htmlNames TABLE 
(
    ID INT IDENTITY(1,1), 
    asciiDecimal INT, 
    htmlName varchar(50)
);

INSERT INTO @htmlNames 
VALUES 
    (34,'"'),
    (38,'&'),
    (60,'<'),
    (62,'>'),
    (160,' '),
    (161,'¡'),
    (162,'¢')
;

DECLARE @inputString varchar(max)= '&test""&';
DECLARE @resultString varchar(max) = @inputString;

-- Simple HTML-decode:
SELECT
    @resultString = Replace(@resultString COLLATE Latin1_General_CS_AS, htmlName, NCHAR(asciiDecimal))
FROM
    @htmlNames
;

SELECT @resultString;
-- Output: &test""&


-- Multiple HTML-decode:
SET @resultString = @inputString;

DECLARE @temp varchar(max) = '';
WHILE @resultString != @temp
BEGIN
    SET @temp = @resultString;

    SELECT
        @resultString = Replace(@resultString COLLATE Latin1_General_CS_AS, htmlName, NCHAR(asciiDecimal))
    FROM
        @htmlNames
    ;
END;

SELECT @resultString;
-- Output: &test""&