Why Can't I Update a Table Inside a MySQL Stored Function or Trigger?
MySQL Error: Updates Prohibited Within Stored Functions/Triggers
When attempting to update a table within a MySQL stored function or trigger, you may encounter the error:
Error: Can't update table 'brandnames' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
Understanding the Error
This error stems from the restriction in MySQL that prohibits modifying a table while an INSERT trigger is executing. Such modifications could potentially lead to deadlocks or infinite recursive loops.
Avoiding the Error
To avoid this error, consider the following approaches:
-
Use NEW and OLD Fields:
- Access new values within the trigger using NEW.fieldname syntax.
- Access old values within the trigger using OLD.fieldname syntax (if performing an UPDATE).
-
Modify the Trigger Context:
- Change the trigger type from AFTER INSERT to BEFORE INSERT.
- Move table modification code outside the stored function or trigger.
Example Using BEFORE INSERT Trigger:
Suppose you have a full_brand_name field and need to create a short_name field containing the first two letters in uppercase:
CREATE TRIGGER `capital` BEFORE INSERT ON `brandnames` FOR EACH ROW BEGIN SET NEW.short_name = CONCAT(UCASE(LEFT(NEW.full_brand_name,1)) , LCASE(SUBSTRING(NEW.full_brand_name,2))) END
The above is the detailed content of Why Can't I Update a Table Inside a MySQL Stored Function or Trigger?. For more information, please follow other related articles on the PHP Chinese website!
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
1377
52
How do you alter a table in MySQL using the ALTER TABLE statement?
Mar 19, 2025 pm 03:51 PM
The article discusses using MySQL's ALTER TABLE statement to modify tables, including adding/dropping columns, renaming tables/columns, and changing column data types.
Explain InnoDB Full-Text Search capabilities.
Apr 02, 2025 pm 06:09 PM
InnoDB's full-text search capabilities are very powerful, which can significantly improve database query efficiency and ability to process large amounts of text data. 1) InnoDB implements full-text search through inverted indexing, supporting basic and advanced search queries. 2) Use MATCH and AGAINST keywords to search, support Boolean mode and phrase search. 3) Optimization methods include using word segmentation technology, periodic rebuilding of indexes and adjusting cache size to improve performance and accuracy.
How do I configure SSL/TLS encryption for MySQL connections?
Mar 18, 2025 pm 12:01 PM
Article discusses configuring SSL/TLS encryption for MySQL, including certificate generation and verification. Main issue is using self-signed certificates' security implications.[Character count: 159]
What are some popular MySQL GUI tools (e.g., MySQL Workbench, phpMyAdmin)?
Mar 21, 2025 pm 06:28 PM
Article discusses popular MySQL GUI tools like MySQL Workbench and phpMyAdmin, comparing their features and suitability for beginners and advanced users.[159 characters]
How do you handle large datasets in MySQL?
Mar 21, 2025 pm 12:15 PM
Article discusses strategies for handling large datasets in MySQL, including partitioning, sharding, indexing, and query optimization.
How do you drop a table in MySQL using the DROP TABLE statement?
Mar 19, 2025 pm 03:52 PM
The article discusses dropping tables in MySQL using the DROP TABLE statement, emphasizing precautions and risks. It highlights that the action is irreversible without backups, detailing recovery methods and potential production environment hazards.
Difference between clustered index and non-clustered index (secondary index) in InnoDB.
Apr 02, 2025 pm 06:25 PM
The difference between clustered index and non-clustered index is: 1. Clustered index stores data rows in the index structure, which is suitable for querying by primary key and range. 2. The non-clustered index stores index key values and pointers to data rows, and is suitable for non-primary key column queries.
How do you create indexes on JSON columns?
Mar 21, 2025 pm 12:13 PM
The article discusses creating indexes on JSON columns in various databases like PostgreSQL, MySQL, and MongoDB to enhance query performance. It explains the syntax and benefits of indexing specific JSON paths, and lists supported database systems.
