Bits of .NET

💾 WP_Query Too Slow? Go Direct.

WP_Query is convenient but slow for complex reports. $wpdb runs raw SQL. 100x faster for large datasets.

📝 Basic $wpdb

global $wpdb;

// Get single value
$user_count = $wpdb->get_var("SELECT COUNT(*) FROM {$wpdb->users}");

// Get single row
$user = $wpdb->get_row("SELECT * FROM {$wpdb->users} WHERE ID = 123");

// Get all results (array of objects)
$users = $wpdb->get_results("SELECT * FROM {$wpdb->users} LIMIT 10");

// Insert (safe, auto-escaped)
$wpdb->insert(
    $wpdb->postmeta,
    [
        'post_id' => 123,
        'meta_key' => 'custom_field',
        'meta_value' => 'Hello World'
    ]
);

// Update
$wpdb->update(
    $wpdb->posts,
    ['post_title' => 'New Title'],
    ['ID' => 123]
);

🎯 Complex Queries

// Top 10 products by sales
$top_products = $wpdb->get_results("
    SELECT p.ID, p.post_title, SUM(oi.meta_value) as total_sales
    FROM {$wpdb->posts} p
    JOIN {$wpdb->postmeta} oi ON p.ID = oi.post_id
    WHERE p.post_type = 'product' 
      AND p.post_status = 'publish'
      AND oi.meta_key = '_order_total'
    GROUP BY p.ID
    ORDER BY total_sales DESC
    LIMIT 10
");

// Search with prepared statement (safe!)
$search = '%' . $wpdb->esc_like($search_term) . '%';
$results = $wpdb->get_results($wpdb->prepare("
    SELECT * FROM {$wpdb->posts}
    WHERE post_title LIKE %s
    AND post_status = 'publish'
", $search));

💡 Best Practices

• Always use $wpdb->prepare() for user input (prevents SQL injection)
• Use $wpdb->prefix for table names (multisite compatible)
• Check for errors: if ($wpdb->last_error) { … }
• For reports, consider caching results with transients