This guide provides an overview of Yahoo! Query Language (YQL) along with information on how to use YQL to retrieve data from Yahoo! Social Directory, MyBlogLog, and data from other Yahoo! Web services. YQL also allows you to retrieve data from external sources such as the New York Times as well as feeds such as RSS and Atom. This guide is intended for software developers who are familiar with SQL, MySQL, or Yahoo! Pipes.

Yahoo! makes a lot of structured data available to developers through its Web services, like Flickr and Local, and through other sources like RSS (news) or CSV documents (finance). There are also numerous external Web services and APIs outside of Yahoo! that provide valuable data. These disparate services require developers to locate the right URLs for accessing them and the documentation for querying them. Data remains isolated and separated, requiring developers to combine and work on the data once it’s returned to them.

The YQL platform provides a mediator service that enables developers to query, filter, and combine data across Yahoo! and beyond. YQL exposes a SQL-like SELECT syntax that is both familiar to developers and expressive enough for getting the right data. Through the SHOW and DESC commands we attempt to make YQL self-documenting, enabling developers to discover the available data sources and structure without opening another web browser or reading a manual.

The YQL Web Service exposes two URLs that are compiled for each query:
The first URL allows you to access both private and public data using OAuth authorization [20]:
http://query.yahooapis.com/v1/yql?q=[command]
If you simply want access to public data, YQL provides a public URL that require no authorization and is wide open:
http://query.yahooapis.com/v1/public?q=[command]

Download pdf Yahoo! Query Language (YQL) Guide