技術標籤：mysqlmysql

Mysql練習

-- 12.25 遞迴建立路徑
T1225
+------+------+
| ID   | PID  |
+------+------+
|    1 |    0 |
|    2 |    1 |
|    3 |    2 |
|    4 |    3 |
+------+------+
結果
+------+------+------------+
| ID   | PID  | PATH       |
+------+------+------------+
|    1 |    0 | 1          |
|    2
 
 |    1 | 1->2       |
|    3 |    2 | 1->2->3    |
|    4 |    3 | 1->2->3->4 |
+------+------+------------+

DROP FUNCTION IF EXISTS f1225;
DELIMITER //  -- 修改結束符

CREATE FUNCTION f1225(Id INT)
RETURNS VARCHAR(4000)
BEGIN
	DECLARE sTemp VARCHAR(4000);
	DECLARE idTemp INTEGER;
	SET sTemp=
 
'1';
	SET idTemp = 1;
	WHILE idTemp < Id DO
		SET sTemp= CONCAT(STemp,'->',cast((idTemp+1) as CHAR));
		SET idTemp = idTemp +1;
	END WHILE;
	RETURN sTemp;
END
//
DELIMITER ;

SELECT ID,PID,f1225(ID) AS PATH FROM T1225;