如何在變量中使用MySQL存儲過程？

Question

我找到了一個存儲過程來計算一個點是在一個多邊形還是在它之外。但是，我遇到了一些麻煩，以適應我的需求。

存儲過程被稱爲如下：

SET @point = PointFromText('POINT(5 5)') ; 
SET @polygon = PolyFromText('POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))'); 
SELECT myWithin(@point, @polygon) AS result; 

我想拉從myPointsTable的緯度和經度，並設置@point到結果。類似於（僞代碼）：

​​

然後讓存儲過程迭代這些點。

同樣，我想從myPolygonTable拉多邊形。像（僞代碼）的東西：

SET @polygon = PolyFromText('POLYGON((SELECT polygonPoints FROM 'myPolygonTable' WHERE town = 'Newport'))'); 

存儲過程是：

DROP FUNCTION IF EXISTS myWithin; 
DELIMITER $$ 
CREATE FUNCTION myWithin(p POINT, poly POLYGON) RETURNS INT(1) DETERMINISTIC 
BEGIN 
DECLARE n INT DEFAULT 0; 
DECLARE pX DECIMAL(9,6); 
DECLARE pY DECIMAL(9,6); 
DECLARE ls LINESTRING; 
DECLARE poly1 POINT; 
DECLARE poly1X DECIMAL(9,6); 
DECLARE poly1Y DECIMAL(9,6); 
DECLARE poly2 POINT; 
DECLARE poly2X DECIMAL(9,6); 
DECLARE poly2Y DECIMAL(9,6); 
DECLARE i INT DEFAULT 0; 
DECLARE result INT(1) DEFAULT 0; 
SET pX = X(p); 
SET pY = Y(p); 
SET ls = ExteriorRing(poly); 
SET poly2 = EndPoint(ls); 
SET poly2X = X(poly2); 
SET poly2Y = Y(poly2); 
SET n = NumPoints(ls); 
WHILE i<n DO 
SET poly1 = PointN(ls, (i+1)); 
SET poly1X = X(poly1); 
SET poly1Y = Y(poly1); 
IF ((((poly1X <= pX) 
&& (pX < poly2X)) || ((poly2X <= pX) 
&& (pX < poly1X))) 
&& (pY > (poly2Y - poly1Y) * (pX - poly1X)/(poly2X - poly1X) + poly1Y)) THEN 
SET result = !result; 
END IF; 
SET poly2X = poly1X; 
SET poly2Y = poly1Y; 
SET i = i + 1; 
END WHILE; 
RETURN result; 
End 
$$ 
DELIMITER ; 

如何在設置變量使用SELECT語句？可能嗎？有沒有更好的辦法？

謝謝。

-Laxmidi

UPDATE：

嗨，

我已經得到了解決問題的一部分。我已經想出瞭如何獲取經緯度。

DROP PROCEDURE IF EXISTS latlongGrabber; 
DELIMITER $$ 
CREATE PROCEDURE latlongGrabber(IN offense_in VARCHAR(255)) 

BEGIN 
    DECLARE latitude_val VARCHAR(255); 
    DECLARE longitude_val VARCHAR(255); 
    DECLARE no_more_rows BOOLEAN; 
    DECLARE latlongGrabber_cur CURSOR FOR 

    SELECT latitude, longitude FROM myTable WHERE offense = offense_in; 
DECLARE CONTINUE HANDLER FOR NOT FOUND SET no_more_rows = TRUE; 

OPEN latlongGrabber_cur; 


the_loop: LOOP 

FETCH latlongGrabber_cur 
INTO latitude_val, longitude_val; 

IF no_more_rows THEN CLOSE latlongGrabber_cur; 
LEAVE the_loop; 
END IF; 
SELECT latitude_val, longitude_val; 
END LOOP the_loop; 
END 
$$ 
DELIMITER ; 

現在，我必須弄清楚如何結合這兩個功能。

-Laxmidi

Answer 1

SELECT INTO語句允許您選擇一個變量。那是你的追求？在這裏看到：

http://dev.mysql.com/doc/refman/5.0/en/select-into-statement.html

SELECT col_name [, col_name] ... 
    INTO var_name [, var_name] ... 
    table_expr