Most efficient way of pulling data out of a string

[kittaneh]

I need to find out the primary key of a sqlite database.Given a string like:\[code\]CREATE TABLE cia (name PRIMARY KEY, population INTEGER)\[/code\]or:\[code\]CREATE TABLE casting(movieid INTEGER, actorid INTEGER, PRIMARY KEY (movieid, actorid))\[/code\]What would the most effective way of getting an array of primary keys be using php?