SubSelect? Join?

I have two tables in which I need to select data from and I don't know what construct to use. The two tables are SY and MV. SY contains stocks and MV contains a log of all price changes of these stocks. I need to produce a report of price changes between the latest price and the previous price and take the difference between the two. I'm using MSSQL. Here are the important fields in my tables:

SY - SY.SYID
MV - MV.SYID
MV - MV.PRICE
MV - MV.DATE

Here is what I have so far:


Code:


SELECT
sy.syid,
sy.sycode,
mv.price,
(SELECT TOP 1(mv.price) FROM MV, SY WHERE mv.syid = sy.syid AND mv.date < '8/27/2007' AND sy.ACTIVE = '1' ORDER BY mv.date DESC) AS lastprice,
(mv.price - (SELECT TOP 1(mv.price) FROM MV, SY WHERE mv.syid = sy.syid AND mv.date < '8/27/2007' AND sy.ACTIVE = '1' ORDER BY mv.date DESC)) AS diff,
(mv.price - (SELECT TOP 1(mv.price) FROM MV, SY WHERE mv.syid = sy.syid AND mv.date < '8/27/2007' AND sy.ACTIVE = '1' ORDER BY mv.date DESC)) /
(SELECT TOP 1(mv.price) FROM MV, SY WHERE mv.syid = sy.syid AND mv.date < '8/27/2007' AND sy.ACTIVE = '1' ORDER BY mv.date DESC) * 100 AS percentdiff,
mv.date
FROM
mv,
sy
WHERE
mv.syid = sy.syid
AND mv.date = '8/27/2007'
AND sy.ACTIVE = '1'
ORDER BY
sy.syid,
mv.date
DESC