Backend Queries

SQL injection prevention requires parameterized queries, which separate SQL code from user input. Use parameterized statements instead of string concatenation to safely pass filters and search terms to your database, protecting against malicious input across SQL, ORM, and query-builder code.

An N+1 problem occurs when fetching a list triggers separate queries for each item's related data. Fix it by eager loading related objects in a single query—for example, fetch products with their categories in one call instead of looping queries, dramatically improving performance.

Optimize queries by avoiding SELECT *, using explicit column selection, adding proper indexing, eager loading related data, and setting query timeouts. These techniques reduce data transfer, disk I/O, and unnecessary processing while preventing runaway queries.

Use transactions to ensure data consistency when performing multiple related updates across tables. Transactions guarantee all changes succeed together or all roll back, preventing partial updates that leave data in an invalid state.

Handle large result sets using pagination with limit and offset parameters, combined with caching strategies to avoid repeated full-table scans. This reduces memory usage and improves response times for data-intensive applications.

Joins combine related tables efficiently, but improper joins can cause performance issues. Use safe joins with explicit join conditions, avoid unnecessary joins, and combine with proper indexing and column selection to maintain fast retrieval.