Posts tagged: sql

Create MySQL stored procedures for batch WordPress database operations like orphan cleanup and category stats, and call them from wpdb.

Create MySQL views to encapsulate complex WordPress JOIN queries into reusable virtual tables you can query from PHP with wpdb.

Build a reliable WordPress plugin migration system with dbDelta, version options and ordered migration functions that run automatically on update.

Use MySQL IN, NOT EXISTS and derived table subqueries to filter and clean WordPress database records efficiently.

Learn INNER JOIN, LEFT JOIN and multi-table joins with practical WordPress SQL examples for posts, meta and taxonomy tables.

Wrap multi-table inserts and updates in MySQL transactions with START TRANSACTION, COMMIT and ROLLBACK via $wpdb.

Use MySQL GROUP BY, ORDER BY, HAVING and aggregate functions to count and summarise WordPress database records.

Learn how to read MySQL EXPLAIN output to identify missing indexes and eliminate full-table scans.

Every WordPress installation ships with a global database abstraction object called $wpdb that wraps all database communication in a clean PHP interface. Understanding how to use it correctly is one of the most important security skills a WordPress developer can have, because SQL injection — the vulnerability where user-supplied data is inserted directly into a…