SELECT S.symbol,
COALESCE(T.xidentity,S.xidentity), COALESCE(T.idsource,S.idsource),
COALESCE(T.exchange,S.exchange), COALESCE(T.type,S.type),
COALESCE(T.subtype,S.subtype), COALESCE(T.xname,S.xname)
FROM Stocks AS S
JOIN
(SELECT symbol,
CASE COUNT(DISTINCT NULLIF(xidentity,''))
WHEN 1 THEN MAX(xidentity) END,
CASE COUNT(DISTINCT NULLIF(idsource,''))
WHEN 1 THEN MAX(idsource) END,
CASE COUNT(DISTINCT NULLIF(exchange,''))
WHEN 1 THEN MAX(exchange) END,
CASE COUNT(DISTINCT NULLIF(type,''))
WHEN 1 THEN MAX(type) END,
CASE COUNT(DISTINCT NULLIF(subtype,''))
WHEN 1 THEN MAX(subtype) END,
CASE COUNT(DISTINCT NULLIF(xname,''))
WHEN 1 THEN MAX(xname) END
FROM Stocks
GROUP BY symbol) AS T
(symbol, xidentity, idsource, exchange, type, subtype, xname)
ON S.symbol = T.symbol

Help others to help you by posting DDL for your table(s) and including
sample data as INSERT statements. That way people can test results and don't
have to guess at datatypes, constraints and keys:

CREATE TABLE Stocks (symbol CHAR(4) NOT NULL, xidentity CHAR(9) NULL,
idsource CHAR(5) NULL, exchange CHAR(4) NULL, type CHAR(5) NULL, subtype
CHAR(6) NULL, xname CHAR(20) NULL /* PRIMARY KEY ??? */)

INSERT INTO Stocks VALUES
('TZA', '901145102', 'CUSIP', 'XNYS', 'Stock', NULL, 'TV AZTECA')
INSERT INTO Stocks VALUES
('TZA', '901145102', NULL, NULL, '', NULL, NULL)
INSERT INTO Stocks VALUES
('WSM', '969904101', 'CUSIP', 'XNYS', 'Stock', NULL, 'WILLIAMS SONOMA')
INSERT INTO Stocks VALUES
('WSM', '969904101', NULL, 'XNYS', 'Stock', NULL, 'WILLIAMS-SONOMA')
INSERT INTO Stocks VALUES
('WSM', '', 'CUSIP', 'XNYS', 'Stock', 'Common', NULL)
INSERT INTO Stocks VALUES
('WSM', NULL, 'CUSIP', 'XASE', 'Stock', NULL, 'WILLIAMS SONOMA')
INSERT INTO Stocks VALUES
('TYC', '902124106', 'CUSIP', 'XNYS', 'Stock', NULL, 'TYCO')
INSERT INTO Stocks VALUES
('TYC', '902124106', 'CUSIP', 'XNYS', 'Stock', NULL, 'TYCO INTERNATIONAL')

--
David Portas
------------
Please reply only to the newsgroup
--