在mysql中建立树形结构_MySQL
bitsCN.com
在mysql中建立树形结构 这个不是什么新东西了,网上有很多方法,我也尝试了其中好的方法,都不尽人意,这是我最后我推荐的方法,共享一下,大家一起讨论,当然难如高手法眼,呵呵。我就直接贴代码了,有问题就联系我。 mysql中要有树形结构我认为表中应该有如写字段: 举例菜单表menu: [sql] create table menu ( id int not null auto_increment, pid int, name varchar(100) not null, nlevel int, scort varchar(8000), primary key (id) ) type = InnoDB; alter table menu add constraint FK_Reference_67 foreign key (pid) references menu (id) on delete restrict on update restrict 创建存储过程genNode_menu: [sql] BEGIN DECLARE Level int ; Set Level=0 ; update menu a inner join (SELECT id,Level,concat(',',ID,',') scort FROM menu WHERE pid is null) b on a.id=b.id set a.nlevel=b.level,a.scort=b.scort; WHILE FOUND_ROWS()>0 DO SET Level=Level+1; update menu a inner join ( SELECT ID,Level,scort FROM menu WHERE nLevel=Level-1) b on a.pid=b.id set a.nlevel=b.level,a.scort=concat(b.sCort,a.ID,','); END WHILE; END 插入数据:[sql] INSERT INTO menu VALUES ('1', null, '菜单1', null, null); INSERT INTO menu VALUES ('2', '1', '菜单1-1', null, null); INSERT INTO menu VALUES ('3', null, '菜单2', null, null); INSERT INTO menu VALUES ('4', '3', '菜单2-1', null, null); INSERT INTO menu VALUES ('5', '4', '菜单2-1-1', null, null); 执行存储过程:[sql] call genNode_menu; 我们看一看menu表现在是什么情况了: 很好,就是这个效果 现在可以按你的需求随便查询了: 比如: [sql] select * from menu a where a.scort not like '%,1,%' order by a.scort 作者 lifaming15 bitsCN.com

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

Big data structure processing skills: Chunking: Break down the data set and process it in chunks to reduce memory consumption. Generator: Generate data items one by one without loading the entire data set, suitable for unlimited data sets. Streaming: Read files or query results line by line, suitable for large files or remote data. External storage: For very large data sets, store the data in a database or NoSQL.

MySQL query performance can be optimized by building indexes that reduce lookup time from linear complexity to logarithmic complexity. Use PreparedStatements to prevent SQL injection and improve query performance. Limit query results and reduce the amount of data processed by the server. Optimize join queries, including using appropriate join types, creating indexes, and considering using subqueries. Analyze queries to identify bottlenecks; use caching to reduce database load; optimize PHP code to minimize overhead.

Backing up and restoring a MySQL database in PHP can be achieved by following these steps: Back up the database: Use the mysqldump command to dump the database into a SQL file. Restore database: Use the mysql command to restore the database from SQL files.

How to insert data into MySQL table? Connect to the database: Use mysqli to establish a connection to the database. Prepare the SQL query: Write an INSERT statement to specify the columns and values to be inserted. Execute query: Use the query() method to execute the insertion query. If successful, a confirmation message will be output.

One of the major changes introduced in MySQL 8.4 (the latest LTS release as of 2024) is that the "MySQL Native Password" plugin is no longer enabled by default. Further, MySQL 9.0 removes this plugin completely. This change affects PHP and other app

To use MySQL stored procedures in PHP: Use PDO or the MySQLi extension to connect to a MySQL database. Prepare the statement to call the stored procedure. Execute the stored procedure. Process the result set (if the stored procedure returns results). Close the database connection.

Creating a MySQL table using PHP requires the following steps: Connect to the database. Create the database if it does not exist. Select a database. Create table. Execute the query. Close the connection.

Oracle database and MySQL are both databases based on the relational model, but Oracle is superior in terms of compatibility, scalability, data types and security; while MySQL focuses on speed and flexibility and is more suitable for small to medium-sized data sets. . ① Oracle provides a wide range of data types, ② provides advanced security features, ③ is suitable for enterprise-level applications; ① MySQL supports NoSQL data types, ② has fewer security measures, and ③ is suitable for small to medium-sized applications.
