mysql查詢最上層父節點
作者：小編 日期：2023-11-12 瀏覽： 次
MySQL查詢最上層父節點
在MySQL數據庫中，有時候我們需要查詢某個節點的最上層父節點。假設我們有一個名為`ree`的表格，它包含以下字段：
`id`: 節點的唯一標識符
`pare_id`: 父節點的id，如果該節點是根節點，則pare_id為ULL
`ame`: 節點的名稱
我們需要建立數據庫和表格：
1. 創建數據庫：
```sql
CREATE DATABASE ree_example;
```
2. 使用數據庫：
```sql
USE ree_example;
```
3. 創建表格：
```sql
CREATE TABLE ree (
id IT PRIMARY KEY,
pare_id IT,
ame VARCHAR(100),
FOREIG KEY (pare_id) REFERECES ree(id)
);
```
接下來，我們插入一些數據：
假設我們有以下節點：
ID: 1, Pare ID: ULL, ame: Roo
ID: 2, Pare ID: 1, ame: A
ID: 3, Pare ID: 1, ame: B
ID: 4, Pare ID: 2, ame: C
ID: 5, Pare ID: 2, ame: D
ID: 6, Pare ID: 3, ame: E
ID: 7, Pare ID: 3, ame: F
ID: 8, Pare ID: 4, ame: G
ID: 9, Pare ID: 4, ame: H
ID: 10, Pare ID: 5, ame: I
ID: 11, Pare ID: 5, ame: J
ID: 12, Pare ID: 6, ame: K
ID: 13, Pare ID: 6, ame: L
ID: 14, Pare ID: 7, ame: M
ID: 15, Pare ID: 7, ame:
ID: 16, Pare ID: 8, ame: O
ID: 17, Pare ID: 8, ame: P
ID: 18, Pare ID: 9, ame: Q
ID: 19, Pare ID: 9, ame: R
ID: 20, Pare ID: 10, ame: S
ID: 21, Pare ID: 10, ame: T
ID: 22, Pare ID: 11, ame: U
ID: 23, Pare ID: 11, ame: V
ID: 24, Pare ID: 12, ame WXY (his is he ode we wa o fid he op pare for)Zu003e To fid he op pare for he ode wih he ame 'WXY', we eed o wrie a query ha recursively checks he pare_id uil i fids a pare_id ha is ULL. Here's a example query ha accomplishes his ask:u003c/reeu003eSELECT 1.ame AS op_pare_ameFROM ree 1JOI ree 2 O 1.id =
2.pare_idWHERE
2.ame = 'WXY'AD 1.pare_id IS ULLu003c/reeu003eTo execue his query ad rerieve he resul i a programmig laguage of your choice (e.g., Pyho), you ca use a MySQL coecor library such as PyMySQL:u003c/pyhou003eimpor pymysqlco = pymysql.coec(hos='localhos', user='userame', password='password', db='ree_example')cursor = co.cursor()query = 2 O 1.id =
2.pare_id WHERE
2.ame = 'WXY' AD 1.pare_id IS ULLoe()[0]pri(f creaig a idex o he `pare_id` colum.u003c/reeu003e