unlink, Semi-Dynamic Pages
UNLOCK TABLES, LOCKing TABLES, LOCK/UNLOCK TABLES
unset, A Simple Shopping Cart
UNSIGNED, MySQL Column Types
UPDATE, Modifying Stored Data, Editing Authors, UPDATE
and TIMESTAMP columns, Date/Time Types
rows affected by, Sending SQL Queries with PHP
WHERE clause, Modifying Stored Data
update logs, Incremental Backups using Update Logs
managing, Incremental Backups using Update Logs
uploading files, Handling File Uploads-Recording Uploaded Files in the Database
with unique file names, Assigning Unique File Names
urlencode, Multipurpose Pages
USE, Creating a Database, USE