FQL Overview

FQL
Overview of FQL
Creating a simple query
Using more advanced syntax
Differences between SQL and FQL
Q & A

FQL: Overview
Facebook Query Language introduced in the early spring of 2007
F8 appeared a little over two months ago
Facebook API calls are just pre-packaged FQL queries

FQL: Overview
Key advantages:
Common syntax for all methods
Condense Facebook queries
Reduce response size

FQL: Overview
FQL is an SQL-like syntax:
SELECT name FROM user WHERE uid = 00000000

FQL: Simple Query
Three parts to a query:
SELECT a field
FROM a table
WHERE a condition is met

FQL: Simple Query
Where do I live?
SELECT current_location FROM user WHERE uid = 00000000

FQL: Simple Query <?xml version="1.0" encoding="UTF-8"?> <users_getInfo_response xmlns="http://api.facebook.com/1.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://api.facebook.com/1.0/ http://api.facebook.com/1.0/facebook.xsd" list="true"> <user> <uid>503802602</uid> <current_location> <city> Toronto </city> <state> Ontario </state> <country> Canada </country> <zip/> </current_location> </user> </users_getInfo_response>

FQL: Simple Query
Has AND , OR , and NOT keywords
Does simple math
Uses basic boolean operators
SELECT uid2 FROM friend WHERE uid1 = 00000000 AND uid2 > (00000000 + 700)

FQL: Simple Query ... <friend_info> <uid2> 00000701 </uid2> </friend_info> <friend_info> <uid2> 00000702 </uid2> </friend_info> <friend_info> <uid2> 00000703 </uid2> </friend_info> ...

FQL: Simple Query
Enhance queries with basic functions
Examples include:
now()
strlen()
substr()
strpos()

FQL: Advanced Query
Use functions and math to construct more accurate responses:
SELECT location FROM event WHERE eid = 2487044119 AND strpos(name,"facebook") AND start_time >= 1186536600

FQL: Advanced Query <?xml version="1.0" encoding="UTF-8"?> <fql_query_response xmlns="http://api.facebook.com/1.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" list="true"> <event> <location> MaRS </location> </event> </fql_query_response>

FQL: Advanced Query
Queries must be “indexable”
Restricted by unique IDs, typically a table's primary ID (“uid”, “pid”, “eid”)
Without an indexable WHERE condition, expect an error

FQL: Advanced Query ... <error_code> 604 </error_code> <error_msg> Your statement is not indexable - the WHERE clause must contain one of the columns marked with a star in http://developers.facebook.com/documentation.php?doc=fql</error_msg> <request_args list="true"> <arg> <key>query</key> <value> SELECT name FROM event WHERE strpos(location,"facebook") </value> </arg> ...

FQL: Advanced Query
Subqueries allow very narrow results to be returned
Chain queries together with IN clause
Limited only by the data itself

FQL: Advanced Query
SELECT eid
FROM event
WHERE eid
IN (
SELECT eid
FROM event_member
WHERE uid = 00000000
AND rsvp_status = "attending"
)
AND location = "mars"

FQL: Advanced Query <?xml version="1.0" encoding="UTF-8"?> <fql_query_response xmlns="http://api.facebook.com/1.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" list="true"> <event> <eid> 2487044119 </eid> </event> </fql_query_response>

FQL: Advanced Query
Some columns contain arrays
Example: current_location also holds city , state , zip
Usage: work_history.company_name

FQL: Versus SQL FQL != fecal

FQL: Versus SQL but... FQL != SQL

FQL: Versus SQL
FQL is designed to be efficient
Improving performance means restricting queries

FQL: Versus SQL
No JOIN
No ORDER BY
No GROUP BY
No LIMIT

FQL: Versus SQL
Limitations may mean too much data is returned
Requires more complicated parsing

FQL: Versus SQL
Each FROM can only be against one table
Not allowed:
SELECT * FROM user, photo_tag WHERE uid = 00000000 AND subject = `flower`

FQL: Versus SQL
Example: display the 5 most recently updated events in Toronto

FQL: Versus SQL
In SQL:
SELECT * FROM event WHERE location = "mars" AND user = 00000000 ORDER BY update_time ASC LIMIT 5

FQL: Versus SQL
In FQL:
SELECT update_time, eid, name, location, venue
FROM event WHERE eid
IN (
SELECT eid FROM event_member WHERE uid = 00000000
)
AND location = "mars"
Then sort the array, and slice it: arsort($result); array_slice($result,0,5);

FQL: Tips
Use the developer tools ( fql.query )
See what is available by investigating the API documentation
Share what you learn on your blog and the developer Wiki

FQL Questions? Craig Saila saila.com [email_address]

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FQL Overview

by Craig Saila on Aug 08, 2007

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FQL Overview — Presentation Transcript