YQL allows users to query and filter data across web services using SQL-like statements. It hides the complexity of web service APIs and provides predefined tables to access popular Yahoo services like Flickr and social media. The YQL console is a browser-based tool to interactively test queries, and results can be returned in XML or JSON format. Queries support operations like filtering, joining tables, paging through results, and being called from JavaScript or PHP.

1. Query the Web with YQL
Sriram Viswanathan
http://slideshare.net/ramace

2. What is YQL?
•Similar to SQL
•Can query, filter and join data across Web services

3. Why YQL?
• Simple, SQL-like
• Hides complexity of Web service API
• Pre-defined tables for popular Yahoo! Web services such as
Flickr, Social and others.
• Supports output format XML, JSON

4. YQL Console
• http://developer.yahoo.com/yql/console/
• Enables you to run YQL statements interactively from your
browser

5. SELECT statement
• SELECT what FROM table WHERE filter
Examples
• select * from social.connections where owner_guid=me
• select contactId from social.connections where owner_guid=me
• select image.imageUrl from social.profile where guid=me

6. Filtering Query Results
Examples
•select * from flickr.photos.search where text='Barcelona’ and
api_key=‘your api key’
•select * from upcoming.events where location in ("San Francisco",
"San Jose”)
•select * from flickr.photos.info where photo_id='7640771676' and
api_key=’your api key'

7. Joining tables with sub-select
Example
select * from social.profile where guid in (select guid from
social.connections where owner_guid=me)

8. Paging and Limits
• select * from flickr.photos.search where text="Cat" and
api_key=”your api key" limit 10
• select * from flickr.photos.search(0,10) where text="Cat" and
api_key=”you api key”
• select * from flickr.photos.search(0,10) where text="Cat" and
api_key=“you api key” limit 5
• select * from flickr.photos.search where text="Cat" and
api_key=“you api key” limit 5 offset 3

9. Using Query Builder
• YQL console includes a simple query builder tool. This tool
allows you to customize and explore YQL statements.

10. Response Data
• Supported response XML, JSON
• Contains diagnostic and results elements
<query ... (attributes such as count)>
<diagnostics>
... (sub-elements such as publiclyCallable)
<results>
... (data returned by the call to YQL)
</results>
</query>

11. YQL using Javascript and PHP
• YUI YQL Utility for Javascript
http://yuilibrary.com/yui/docs/yql/
• YQL call from PHP
http://developer.yahoo.com/yql/guide/yql-code-
examples.html#yql_php

12. Usage Information and
Limitations
• YQL has a performance uptime target of over 99.5%.
• YQL relies on the correct operation of the Web services and
content providers it accesses.
• Per application limit (identified by your Access Key): 100,000
calls per day.
• Per IP limits: /v1/public/*: 2,000 calls per hour; /v1/yql/*: 20,000
calls per hour.
• YQL rate limits are subject to the rate limits of other Yahoo! and
3rd-party Web services.

13. References
http://developer.yahoo.com/yql/
http://developer.yahoo.com/yql/guide/
http://yuilibrary.com/yui/docs/yql/
http://developer.yahoo.com/yql/guide/yql-code-
examples.html#yql_php

14. Thank You!
&
happy hacking