>>368
如何せんこちらは株には疎いので...

コンマ以下の数字も必要なの？
値の入っている(テーブルの)フィールドを通貨型にしてみれば？
(小数点以下4位まで可能)

> もし､同じクエリでもOK！ってな場合なら､同様の差を出すようにするのは困難？

SELECT j_Data.IDｊD, j_Data.Data, [225t].[225O], [225t].[225H], [225t].[225L], [225t].[225C], [225t]![225C]-Nz(Q1![225C],0) AS 225Ch, [226t].[226O], [226t].[226H], [226t].[226L], [226t].[226C], [226t]![226C]-Nz([Q2]![226C],0) AS 226Ch
FROM (((j_Data LEFT JOIN 225t ON j_Data.IDｊD=[225t].ID225t) LEFT JOIN (SELECT [225t]![ID225t]+1 AS ID225t, [225t].[225C]
FROM 225t, 225t AS A
WHERE (((A.ID225t)=[225t]![ID225t]))
) AS Q1 ON j_Data.IDｊD=Q1.ID225t) LEFT JOIN 226t ON j_Data.IDｊD=[226t].ID226t) LEFT JOIN (SELECT [226t]!ID226t+1 AS ID226t, [226t].[226C]
FROM 226t AS A, 226t
WHERE (((A.ID226t)=[226t]![ID226t]))) AS Q2 ON j_Data.IDｊD=[Q2].ID226t;

こんな感じでやってく...分からないなら
サブクエリを使わないで
Q1クエリ
SELECT [225t]![ID225t]+1 AS ID225t, [225t].[225C]
FROM 225t, 225t AS A
WHERE (((A.ID225t)=[225t]![ID225t]));
Q2クエリ
SELECT [226t]![ID226t]+1 AS ID226t, [226t].[226C]
FROM 226t, 226t AS A
WHERE (((A.ID226t)=[226t]![ID226t]));
のようにクエリを作ってGUI(デザインビュー)で繋げた方(結合線)がいいぞ