Home Database Mysql Tutorial What to do with mysql error 1022

What to do with mysql error 1022

Feb 16, 2023 am 09:43 AM
mysql

mysql error 1022 is caused by duplicate foreign key names. The solution is: 1. Use the "select * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE where CONSTRAINT_NAME='...'" command to find duplicate foreign key names; 2. Just rename the foreign key name.

What to do with mysql error 1022

The operating environment of this tutorial: Windows 10 system, MySQL version 5.7, Dell G3 computer.

What to do with mysql error 1022?

mysql error Error Code: 1022. Can't write; duplicate key in table `xxx`

Explanation: This error is a duplicate foreign key name

Find duplicate foreign key names, where they are used, the sql is as follows:

select * from INFORMATION_SCHEMA.KEY_COLUMN_USAGE  where CONSTRAINT_NAME='重复的外键名称'
Copy after login

If there is no problem, just rename it.

Related expansion:

1 Definition of foreign key

A foreign key is a column in a table that is included in the primary key of another table.

Foreign key is also a type of index, which associates two tables by pointing a column in one table to the primary key in another table.

A table can have one foreign key, or there can be multiple foreign keys that are associated with multiple tables.

2 The role of foreign keys

The main role of foreign keys is to ensure the consistency and integrity of data and reduce data redundancy.

Mainly reflected in the following two aspects:

  • Prevent execution

Insert a new row from the table, its foreign key value The insertion is blocked if the primary key value is not the main table.

Modify the foreign key value from the table. If the new value is not the primary key value of the main table, the modification is blocked.

Delete a row from the master table, and its primary key value will prevent deletion if it exists in the slave table (if you want to delete it, you must first delete the relevant rows from the slave table).

The primary table modifies the primary key value. If the old value exists in the secondary table, the modification is prevented (if you want to modify it, you must first delete the relevant rows from the secondary table).

  • Cascade execution

Delete rows from the main table and delete related rows from the table together.

Modify the primary key value of the main table, and modify the foreign key value of the related rows of the slave table together.

3 Foreign key creation restrictions

The parent table must already exist in the database, or be the table currently being created.

If the latter is the case, the parent table and the child table are the same table. Such a table is called a self-referential table, and this structure is called self-referential integrity.

The primary key must be defined for the parent table.

The number of columns in the foreign key must be the same as the number of columns in the primary key of the parent table.

The two tables must be InnoDB tables. MyISAM tables do not currently support foreign keys.

Foreign key columns must be indexed. MySQL 4.1.2 and later versions will automatically create indexes when establishing foreign keys, but in earlier versions, they need to be created explicitly.

The columns of the two tables in the foreign key relationship must have similar data types, that is, columns that can be converted to each other. For example, int and tinyint can be used, but int and char cannot.

Recommended learning: "MySQL Video Tutorial"

The above is the detailed content of What to do with mysql error 1022. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

MySQL: Simple Concepts for Easy Learning MySQL: Simple Concepts for Easy Learning Apr 10, 2025 am 09:29 AM

MySQL is an open source relational database management system. 1) Create database and tables: Use the CREATEDATABASE and CREATETABLE commands. 2) Basic operations: INSERT, UPDATE, DELETE and SELECT. 3) Advanced operations: JOIN, subquery and transaction processing. 4) Debugging skills: Check syntax, data type and permissions. 5) Optimization suggestions: Use indexes, avoid SELECT* and use transactions.

How to open phpmyadmin How to open phpmyadmin Apr 10, 2025 pm 10:51 PM

You can open phpMyAdmin through the following steps: 1. Log in to the website control panel; 2. Find and click the phpMyAdmin icon; 3. Enter MySQL credentials; 4. Click "Login".

MySQL: An Introduction to the World's Most Popular Database MySQL: An Introduction to the World's Most Popular Database Apr 12, 2025 am 12:18 AM

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

Why Use MySQL? Benefits and Advantages Why Use MySQL? Benefits and Advantages Apr 12, 2025 am 12:17 AM

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

How to use single threaded redis How to use single threaded redis Apr 10, 2025 pm 07:12 PM

Redis uses a single threaded architecture to provide high performance, simplicity, and consistency. It utilizes I/O multiplexing, event loops, non-blocking I/O, and shared memory to improve concurrency, but with limitations of concurrency limitations, single point of failure, and unsuitable for write-intensive workloads.

MySQL and SQL: Essential Skills for Developers MySQL and SQL: Essential Skills for Developers Apr 10, 2025 am 09:30 AM

MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.

MySQL's Place: Databases and Programming MySQL's Place: Databases and Programming Apr 13, 2025 am 12:18 AM

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

How to build a SQL database How to build a SQL database Apr 09, 2025 pm 04:24 PM

Building an SQL database involves 10 steps: selecting DBMS; installing DBMS; creating a database; creating a table; inserting data; retrieving data; updating data; deleting data; managing users; backing up the database.

See all articles