So implementieren Sie eine rekursive Abfrage in MySQL

MySQL-Methode zum Implementieren einer rekursiven Abfrage: Erstellen Sie zuerst eine Tabelle und initialisieren Sie die Daten. Führen Sie dann eine Rekursion nach unten durch und verwenden Sie die Funktionen [find_in_set()] und [group_concat()], um die rekursive Abfrage zu implementieren.

Die Betriebsumgebung dieses Tutorials: Windows7-System, MySQL-Version 8.0.22, Thinkpad T480-Computer.

Kostenlose Lernempfehlung: MySQL-Tutorial(Video)

MySQL-Methode zur Implementierung einer rekursiven Abfrage:

1. Tabelle erstellen

DROP TABLE IF EXISTS `t_areainfo`;
CREATE TABLE `t_areainfo` (
 `id` int(11) NOT '0' AUTO_INCREMENT,
 `level` int(11) DEFAULT '0',
 `name` varchar(255) DEFAULT '0',
 `parentId` int(11) DEFAULT '0',
 `status` int(11) DEFAULT '0',
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=65 DEFAULT CHARSET=utf8;

2. Erste Daten

INSERT INTO `t_areainfo` VALUES ('1', '0', '中国', '0', '0');
INSERT INTO `t_areainfo` VALUES ('2', '0', '华北区', '1', '0');
INSERT INTO `t_areainfo` VALUES ('3', '0', '华南区', '1', '0');
INSERT INTO `t_areainfo` VALUES ('4', '0', '北京', '2', '0');
INSERT INTO `t_areainfo` VALUES ('5', '0', '海淀区', '4', '0');
INSERT INTO `t_areainfo` VALUES ('6', '0', '丰台区', '4', '0');
INSERT INTO `t_areainfo` VALUES ('7', '0', '朝阳区', '4', '0');
INSERT INTO `t_areainfo` VALUES ('8', '0', '北京XX区1', '4', '0');
INSERT INTO `t_areainfo` VALUES ('9', '0', '北京XX区2', '4', '0');
INSERT INTO `t_areainfo` VALUES ('10', '0', '北京XX区3', '4', '0');
INSERT INTO `t_areainfo` VALUES ('11', '0', '北京XX区4', '4', '0');
INSERT INTO `t_areainfo` VALUES ('12', '0', '北京XX区5', '4', '0');
INSERT INTO `t_areainfo` VALUES ('13', '0', '北京XX区6', '4', '0');
INSERT INTO `t_areainfo` VALUES ('14', '0', '北京XX区7', '4', '0');
INSERT INTO `t_areainfo` VALUES ('15', '0', '北京XX区8', '4', '0');
INSERT INTO `t_areainfo` VALUES ('16', '0', '北京XX区9', '4', '0');
INSERT INTO `t_areainfo` VALUES ('17', '0', '北京XX区10', '4', '0');
INSERT INTO `t_areainfo` VALUES ('18', '0', '北京XX区11', '4', '0');
INSERT INTO `t_areainfo` VALUES ('19', '0', '北京XX区12', '4', '0');
INSERT INTO `t_areainfo` VALUES ('20', '0', '北京XX区13', '4', '0');
INSERT INTO `t_areainfo` VALUES ('21', '0', '北京XX区14', '4', '0');
INSERT INTO `t_areainfo` VALUES ('22', '0', '北京XX区15', '4', '0');
INSERT INTO `t_areainfo` VALUES ('23', '0', '北京XX区16', '4', '0');
INSERT INTO `t_areainfo` VALUES ('24', '0', '北京XX区17', '4', '0');
INSERT INTO `t_areainfo` VALUES ('25', '0', '北京XX区18', '4', '0');
INSERT INTO `t_areainfo` VALUES ('26', '0', '北京XX区19', '4', '0');
INSERT INTO `t_areainfo` VALUES ('27', '0', '北京XX区1', '4', '0');
INSERT INTO `t_areainfo` VALUES ('28', '0', '北京XX区2', '4', '0');
INSERT INTO `t_areainfo` VALUES ('29', '0', '北京XX区3', '4', '0');
INSERT INTO `t_areainfo` VALUES ('30', '0', '北京XX区4', '4', '0');
INSERT INTO `t_areainfo` VALUES ('31', '0', '北京XX区5', '4', '0');
INSERT INTO `t_areainfo` VALUES ('32', '0', '北京XX区6', '4', '0');
INSERT INTO `t_areainfo` VALUES ('33', '0', '北京XX区7', '4', '0');
INSERT INTO `t_areainfo` VALUES ('34', '0', '北京XX区8', '4', '0');
INSERT INTO `t_areainfo` VALUES ('35', '0', '北京XX区9', '4', '0');
INSERT INTO `t_areainfo` VALUES ('36', '0', '北京XX区10', '4', '0');
INSERT INTO `t_areainfo` VALUES ('37', '0', '北京XX区11', '4', '0');
INSERT INTO `t_areainfo` VALUES ('38', '0', '北京XX区12', '4', '0');
INSERT INTO `t_areainfo` VALUES ('39', '0', '北京XX区13', '4', '0');
INSERT INTO `t_areainfo` VALUES ('40', '0', '北京XX区14', '4', '0');
INSERT INTO `t_areainfo` VALUES ('41', '0', '北京XX区15', '4', '0');
INSERT INTO `t_areainfo` VALUES ('42', '0', '北京XX区16', '4', '0');
INSERT INTO `t_areainfo` VALUES ('43', '0', '北京XX区17', '4', '0');
INSERT INTO `t_areainfo` VALUES ('44', '0', '北京XX区18', '4', '0');
INSERT INTO `t_areainfo` VALUES ('45', '0', '北京XX区19', '4', '0');
INSERT INTO `t_areainfo` VALUES ('46', '0', 'xx省1', '1', '0');
INSERT INTO `t_areainfo` VALUES ('47', '0', 'xx省2', '1', '0');
INSERT INTO `t_areainfo` VALUES ('48', '0', 'xx省3', '1', '0');
INSERT INTO `t_areainfo` VALUES ('49', '0', 'xx省4', '1', '0');
INSERT INTO `t_areainfo` VALUES ('50', '0', 'xx省5', '1', '0');
INSERT INTO `t_areainfo` VALUES ('51', '0', 'xx省6', '1', '0');
INSERT INTO `t_areainfo` VALUES ('52', '0', 'xx省7', '1', '0');
INSERT INTO `t_areainfo` VALUES ('53', '0', 'xx省8', '1', '0');
INSERT INTO `t_areainfo` VALUES ('54', '0', 'xx省9', '1', '0');
INSERT INTO `t_areainfo` VALUES ('55', '0', 'xx省10', '1', '0');
INSERT INTO `t_areainfo` VALUES ('56', '0', 'xx省11', '1', '0');
INSERT INTO `t_areainfo` VALUES ('57', '0', 'xx省12', '1', '0');
INSERT INTO `t_areainfo` VALUES ('58', '0', 'xx省13', '1', '0');
INSERT INTO `t_areainfo` VALUES ('59', '0', 'xx省14', '1', '0');
INSERT INTO `t_areainfo` VALUES ('60', '0', 'xx省15', '1', '0');
INSERT INTO `t_areainfo` VALUES ('61', '0', 'xx省16', '1', '0');
INSERT INTO `t_areainfo` VALUES ('62', '0', 'xx省17', '1', '0');
INSERT INTO `t_areainfo` VALUES ('63', '0', 'xx省18', '1', '0');
INSERT INTO `t_areainfo` VALUES ('64', '0', 'xx省19', '1', '0');

3. Abwärtsrekursion

Verwenden Sie die find_in_set()函数和group_concat()-Funktion, um eine rekursive Abfrage zu implementieren:

DROP FUNCTION IF EXISTS queryChildrenAreaInfo;
DELIMITER ;;
CREATE FUNCTION queryChildrenAreaInfo(areaId INT)
RETURNS VARCHAR(4000)
BEGIN
DECLARE sTemp VARCHAR(4000);
DECLARE sTempChd VARCHAR(4000);
SET sTemp='$';
SET sTempChd = CAST(areaId AS CHAR);
WHILE sTempChd IS NOT NULL DO
SET sTemp= CONCAT(sTemp,',',sTempChd);
SELECT GROUP_CONCAT(id) INTO sTempChd FROM t_areainfo WHERE FIND_IN_SET(parentId,sTempChd)>0;
END WHILE;
RETURN sTemp;
END
;;
DELIMITER ;

4. Aufrufmethode

SELECT queryChildrenAreaInfo(1);

Fragen Sie alle Knoten unter der ID „4“ ab rreee

5. Aufwärtsrekursion

SELECT * FROM t_areainfo WHERE FIND_IN_SET(id,queryChildrenAreaInfo(4));

6. Aufrufmethode

Fragen Sie alle übergeordneten Knoten des Knotens mit der ID „7“ ab:

DROP FUNCTION IF EXISTS queryChildrenAreaInfo1;
DELIMITER;;
CREATE FUNCTION queryChildrenAreaInfo1(areaId INT)
RETURNS VARCHAR(4000)
BEGIN
DECLARE sTemp VARCHAR(4000);
DECLARE sTempChd VARCHAR(4000);
SET sTemp='$';
SET sTempChd = CAST(areaId AS CHAR);
SET sTemp = CONCAT(sTemp,',',sTempChd);
SELECT parentId INTO sTempChd FROM t_areainfo WHERE id = sTempChd;
WHILE sTempChd <> 0 DO
SET sTemp = CONCAT(sTemp,&#39;,&#39;,sTempChd);
SELECT parentId INTO sTempChd FROM t_areainfo WHERE id = sTempChd;
END WHILE;
RETURN sTemp;
END
;;
DELIMITER ;

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