wp-database

Use when a WordPress plugin needs a custom database table — creating with dbDelta (strict SQL format: two spaces before PRIMARY KEY, no trailing comma), writing versioned upgrade routines with version_compare and register_activation_hook, querying with $wpdb prepared statements (prepare, insert, update, delete, get_row, get_results, get_var), debugging with $wpdb->last_error or SAVEQUERIES, schema migrations between plugin versions, uninstall cleanup, multisite table handling with switch_to_blog / get_sites, or seeding test/preview data into custom tables. Triggers: "create a custom table", "dbDelta not working", "dbDelta not creating my table", "write a migration", "wpdb query", "wpdb prepare", "slow query on my custom table", "upgrade my database schema", "add a column to my table", "seed test data", "how do I store this in a custom table", "database upgrade routine", "table not being created on activation", "prepare placeholder wrong", "last_error is empty after query", "SAVEQUERIES debug", "version_compare for db upgrade", "register_activation_hook table", "wpdb prefix table name", "uninstall drops table", "multisite per-site table", "charset_collate missing". Not for: WordPress options API or post meta — use those when a custom table is not needed.