MySQL analog Oracle adjacency Model tree Processing

Source: Internet
Author: User
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There are many kinds of database processing models for hierarchy, which can be designed according to their own requirements. Of course, the simplest and easiest model is the so-called adjacency model. In this regard, other databases, such as Oracle, provide a ready-made analytical approach to connect by, and MySQL is somewhat weak in this regard. Just be able to implement Oracle-like analytics with MySQL stored procedures


In this way, first create a simple tables.
CREATE TABLE Country (ID number (2) not NULL,  name varchar is NOT NULL), CREATE TABLE Country_relation (ID number (2), C1/>parentid number (2));




Insert some data
--Table Country.insert into country (id,name) values (0, ' Earth '); Insert to 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 Co Untry (Id,name) VALUES (5, ' Asia '), insert into country (Id,name) VALUES (6, ' Africa ') and insert into country (id,name) VALUES ( 7, ' Australia '); insert into country (id,name) VALUES (8, ' Canada '); Insert to Country (Id,name) VALUES (9, ' central America INSERT into country (id,name) VALUES ("Island Nations"), insert into country (id,name) values (one, ' one states '); SERT into country (id,name) VALUES ("Alabama"), insert into country (id,name) VALUES ("Alaska"), insert into country ( Id,name) VALUES ("Arizona"), insert into country (id,name) VALUES ("Arkansas"), insert into country (id,name) VALUES ( ' 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 Coun Try_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);



Inside Oracle. It's easier to do these things. are provided by the system.


For example, the following four scenarios:
1). View depth,

Select Max (level) ' level ' from country_relation a start with A.parentid are nullconnect by PRIOR a.id = A.parentidorder by level;     Level----------         4 time:  00:00:00.03




2). View leaf nodes
Select name from (select B.name, connect_by_isleaf "IsLeaf" from Country_relation a inner joins country B on (a.id = b.id) s Tart with A.parentid are NULL connect by prior a.id = A.parentid) T where T. " IsLeaf "= 1; NAME--------------------------------------------------canadacentral Americaisland Nationsalabamaalaskaarizonaarkansascaliforniasouth Americaeuropeasiaafricaaustralia has selected 13 rows. Time used:  00:00:00.01



3) View the root node
Select Connect_by_root b.namefrom country_relation a INNER join country B on (a.id = b.id) Start with A.parentid is NULL C Onnect by a.id = A.parentid CONNECT_BY_ROOTB. NAME--------------------------------------------------Earth Time:  00:00:00.01



4). View Path
Select Sys_connect_by_path (B.name, '/') "path" from Country_relation a inner joins country B on (a.id = b.id) Start with A.P Arentid is a 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/ 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 has selected 16 rows.

Time used: 00:00:00.01





Let's look at how the above four scenarios are implemented in MySQL:
The first three kinds are simpler. Very easy to write SQL.
1) View Depth
Mysql> SELECT COUNT (DISTINCT ifnull (parentid,-1)) as level from country_relation;+-------+| Level |+-------+|     4 |+-------+1 row in Set (0.00 sec)



2) View the root node
Mysql> Select B. ' Name ' as Root_node from    (-a    select  ID from country_relation WHERE parentid is NU LL    -C) as a, country as b WHERE a.id = b.id;+-----------+| Root_node |+-----------+| Earth     |+-----------+1 row in Set (0.00 sec)



3). View leaf nodes
Mysql> Select B. ' Name ' as Leaf_node from    (-a    select  ID from country_relation WHERE ID not in (SEL ECT 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)





4) View Path
This piece does not have a simple SQL implementation. It is only possible to use MySQL stored procedures to achieve the same functionality.
Stored procedure Code such as the following:


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 (+) 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 (+) DEFAULT '; DECLARE CR1 CURSOR for SELECT parentid from Country_relation WHERE ParentID was not NULL GROUP by ParentID ORDER by parent        ID 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 Parent          id = 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 to CNT; WhileI2 < 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;    SELECT Node_path from Tmp_country_list; end$ $DELIMITER;




Call Result:
Mysql> call Sp_show_list (); +-----------------------------------------------+| Node_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 |+-----------------------------------------------+16 rows in Set (0.04 sec) Query OK, 0 rows affected (0.08 sec) 


MySQL analog Oracle adjacency Model tree Processing

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