Hi,
If you are only dealing with squares it is quite easy.
Firstly you only need the top left and bottom right co-ordinates:
CREATE TABLE Squares
(CellNo CHAR(2) NOT NULL,
TopLeftX INT NOT NULL,
TopLeftY INT NOT NULL,
BottomRightX INT NOT NULL,
BottomRightY INT NOT NULL);
INSERT INTO Squares VALUES
('A1', 0, 0, 100, 100),
('A2', 0, 101, 100, 200),
('B1', 101, 0, 200, 100),
('B2', 101, 101, 200, 200);
Secondly, to make it scale to 10,000+ records you need to index the four co-ordinates. I would cluster the table on these columns:
ALTER TABLE Squares
ADD CONSTRAINT SquaresCoordinates UNIQUE CLUSTERED (TopLeftX, TopLeftY, BottomRightX, BottomRightY);
Lastly, you just need to query for any values where the X and the Y each falls between the upper left and bottom right range. You can use a join as Dwain showed you above or you can specify the points in a where clause.
SELECT
*
FROM
Squares
WHERE
(25 BETWEEN TopLeftX AND BottomRightX
AND 130 BETWEEN TopLeftY AND BottomRightY)
OR
(105 BETWEEN TopLeftX AND BottomRightX
AND 40 BETWEEN TopLeftY AND BottomRightY);
