create table country ( id number(2) not null, name varchar(60) not null);
create table country_relation (id number(2), parentid number(2));
create table country_relation (id number(2), parentid number(2)); 插入一些數據,代碼如下:
-- Table country. insert into country (id,name) values (0,'Earth'); insert into country (id,name) values (2,'North America'); insert into country (id,name) values (3,'South America'); insert into country (id,name) values (4,'Europe'); insert into country (id,name) values (5,'Asia'); insert into country (id,name) values (6,'Africa'); insert into country (id,name) values (7,'Australia'); insert into country (id,name) values (8,'Canada'); insert into country (id,name) values (9,'Central America'); insert into country (id,name) values (10,'Island Nations'); insert into country (id,name) values (11,'United States'); insert into country (id,name) values (12,'Alabama'); insert into country (id,name) values (13,'Alaska'); insert into country (id,name) values (14,'Arizona'); insert into country (id,name) values (15,'Arkansas'); insert into country (id,name) values (16,'California');
-- Table country_relation. insert into country_relation (id,parentid) values (0,NULL); insert into country_relation (id,parentid) values (2,0); insert into country_relation (id,parentid) values (3,0); insert into country_relation (id,parentid) values (4,0); insert into country_relation (id,parentid) values (5,0); insert into country_relation (id,parentid) values (6,0); insert into country_relation (id,parentid) values (7,0); insert into country_relation (id,parentid) values (8,2); insert into country_relation (id,parentid) values (9,2); insert into country_relation (id,parentid) values (10,2); insert into country_relation (id,parentid) values (11,2); insert into country_relation (id,parentid) values (12,11); insert into country_relation (id,parentid) values (13,11); insert into country_relation (id,parentid) values (14,11); insert into country_relation (id,parentid) values (15,11); insert into country_relation (id,parentid) values (16,11); 在Oracle 里面,對這些操作就比較簡單了,都是系統提供的,比如下面四種情形.
1).查看深度,代碼如下:
select max(level) "level" from COUNTRY_RELATION a start with a.parentid is NULL connect by PRIOR a.id = a.PARENTID order by level;
level ---------- 4
--已用時間: 00: 00: 00.03 2).查看葉子節點,代碼如下:
select name from ( select b.name, connect_by_isleaf "isleaf" from COUNTRY_RELATION a inner join country b on (a.id = b.id) start with a.parentid is NULL connect by prior a.id = a.PARENTID ) T where T."isleaf" = 1;
NAME -------------------------------------------------- Canada Central America Island Nations Alabama Alaska Arizona Arkansas California South America Europe Asia Africa Australia
--已選擇13行。
--已用時間: 00: 00: 00.01 3).查看ROOT節點,代碼如下:
select connect_by_root b.name from COUNTRY_RELATION a inner join country b on (a.id = b.id) start with a.parentid is NULL connect by a.id = a.PARENTID --phpfensi.com CONNECT_BY_ROOTB.NAME -------------------------------------------------- Earth
--已用時間: 00: 00: 00.01 4).查看路徑,代碼如下:
select sys_connect_by_path(b.name,'/') "path" from COUNTRY_RELATION a inner join country b on (a.id = b.id) start with a.parentid is NULL connect by prior a.id = a.PARENTID order by level,a.id;
path -------------------------------------------------- /Earth /Earth/North America /Earth/South America /Earth/Europe /Earth/Asia /Earth/Africa /Earth/Australia /Earth/North America/Canada /Earth/North America/Central America /Earth/North America/Island Nations /Earth/North America/United States /Earth/North America/United States/Alabama /Earth/North America/United States/Alaska /Earth/North America/United States/Arizona /Earth/North America/United States/Arkansas /Earth/North America/United States/California
mysql> SELECT COUNT(DISTINCT IFNULL(parentid,-1)) AS LEVEL FROM country_relation ; +-------+ | LEVEL | +-------+ | 4 | +-------+ 1 row in set (0.00 sec) 2)查看ROOT節點,代碼如下:
mysql> SELECT b.`name` AS root_node FROM -> ( -> SELECT id FROM country_relation WHERE parentid IS NULL -> ) AS a, country AS b WHERE a.id = b.id; +-----------+ | root_node | +-----------+ | Earth | +-----------+ 1 row in set (0.00 sec) 3).查看葉子節點,代碼如下:
mysql> SELECT b.`name` AS leaf_node FROM -> ( -> SELECT id FROM country_relation WHERE id NOT IN (SELECT IFNULL(parentid, -1) FROM country_relation) -> ) AS a, country AS b WHERE a.id = b.id; +-----------------+ | leaf_node | +-----------------+ | South America | | Europe | | Asia | | Africa | | Australia | | Canada | | Central America | | Island Nations | | Alabama | | Alaska | | Arizona | | Arkansas | | California | +-----------------+ 13 rows in set (0.00 sec)
mysql> 4)查看路徑
這一塊沒有簡單的SQL實現,不過可以用MySQL的存儲過程來實現同樣的功能,存儲過程代碼如下:
DELIMITER $$ USE `t_girl`$$ DROP PROCEDURE IF EXISTS `sp_show_list`$$ CREATE DEFINER=`root`@`localhost` PROCEDURE `sp_show_list`() BEGIN -- Created by ytt 2014/11/04. -- Is equal to oracle's connect by syntax. -- Body. DROP TABLE IF EXISTS tmp_country_list; CREATE TEMPORARY TABLE tmp_country_list (node_level INT UNSIGNED NOT NULL, node_path VARCHAR(1000) NOT NULL); -- Get the root node. INSERT INTO tmp_country_list SELECT 1, CONCAT('/',id) FROM country_relation WHERE parentid IS NULL; -- Loop within all parent node. cursor1:BEGIN DECLARE done1 INT DEFAULT 0; DECLARE i1 INT DEFAULT 1; DECLARE v_parentid INT DEFAULT -1; DECLARE v_node_path VARCHAR(1000) DEFAULT ''; DECLARE cr1 CURSOR FOR SELECT parentid FROM country_relation WHERE parentid IS NOT NULL GROUP BY parentid ORDER BY parentid ASC; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done1 = 1;
OPEN cr1;
loop1:LOOP FETCH cr1 INTO v_parentid; IF done1 = 1 THEN LEAVE loop1; END IF; SET i1 = i1 + 1;
label_path:BEGIN DECLARE done2 INT DEFAULT 0; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done2 = 1; -- Get the upper path. SELECT node_path FROM tmp_country_list WHERE node_level = i1 - 1 AND LOCATE(v_parentid,node_path) > 0 INTO v_node_path; -- Escape the outer not found exception. IF done2 = 1 THEN SET done2 = 0; END IF; INSERT INTO tmp_country_list SELECT i1,CONCAT(IFNULL(v_node_path,''),'/',id) FROM country_relation WHERE parentid = v_parentid; END; END LOOP;
CLOSE cr1;
END; -- Update node's id to its real name. update_name_label:BEGIN DECLARE cnt INT DEFAULT 0; DECLARE i2 INT DEFAULT 0; SELECT MAX(node_level) FROM tmp_country_list INTO cnt; WHILE i2 < cnt DO UPDATE tmp_country_list AS a, country AS b SET a.node_path = REPLACE(a.node_path,CONCAT('/',b.id),CONCAT('/',b.name)) WHERE LOCATE(CONCAT('/',b.id),a.node_path) > 0; SET i2 = i2 + 1; END WHILE; END;
