SQL
SQL - Triggers
SQL triggers are special types of stored procedures that are automatically executed or fired when certain events occur in the database. Triggers can be used to enforce business rules, validate data, audit changes, and synchronize tables. Here's a detailed tutorial on how to create, use, and manage SQL triggers.
Basic Syntax
CREATE TRIGGER trigger_name
{BEFORE | AFTER | INSTEAD OF} {INSERT | UPDATE | DELETE}
ON table_name
FOR EACH ROW
BEGIN
-- Trigger logic
END;
General Tips!
- Use Proper Indexing: Index frequently queried columns to improve query performance, but avoid over-indexing as it can slow down write operations.
- Write Efficient Queries: Optimize your queries by selecting only the necessary columns, avoiding SELECT *, and using joins wisely.
- Normalize Your Data: Organize your database into normalized tables to reduce redundancy and improve data integrity.
- Use Transactions: Ensure data consistency and integrity by wrapping multiple related operations in transactions, especially in multi-step processes.
- Understand and Use SQL Functions: Leverage built-in SQL functions for data manipulation and retrieval, such as aggregate functions (SUM, COUNT) and string functions (CONCAT, SUBSTRING).