mysql recursively query upper and lower levels

Recently, I encountered a regional query problem in a project, involving recursion. The processing efficiency in java code was found to be low, so I considered using sql recursion.

Paste a table structure:

1. Query the lower-level method

CREATE FUNCTION getChildrenOrg (orgid INT) RETURNS VARCHAR (4000)
BEGIN
DECLARE oTemp VARCHAR (4000);
DECLARE oTempChild VARCHAR (4000);
SET oTemp = '';
SET oTempChild = CAST(orgid AS CHAR);
WHILE oTempChild IS NOT NULL DO
SET oTemp = CONCAT(oTemp, ',', oTempChild);
SELECT
	GROUP_CONCAT(areaid) INTO oTempChild
FROM
	area
WHERE
	FIND_IN_SET(parentid, oTempChild) > 0;
END
WHILE;
RETURN oTemp;
END

Call method (query all subordinates in the area where the areaid is 620000 (Gansu))

SELECT
	*
FROM
	area
WHERE
	FIND_IN_SET(
		areaid,
		getChildrenOrg (620000)
	)

result:

1. Query the superior method

SELECT *
    FROM ( 
        SELECT 
                @r AS _id, 
                (SELECT @r := parentid FROM area WHERE areaid = _id) AS parent_id, 
                 @l := @l + 1 AS lvl 
        FROM 
                (SELECT @r := 330324, @l := 0) vars, 
                area h 
        WHERE @r <> 0) T1 
    JOIN area T2 
    ON T1._id = T2.areaid
ORDER BY areaid;

Note that 330324 is the child node areaid

The result is as follows: