WebSQL is a SQL-like（）language for extracting information from the web.Its capabilities for performing navigation of web （）make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a （），all the pages that can be reached from a given URL through （）that match a pattern，or a combination of both.WebSQL also provides transparent access to index servers that can be queried via the Common （）Interface.