Find polygon that contains all linestring records in PostGIS table

Question

I'm still pretty new to this stuff, so bear with me. In PostGIS how could I find a polygon that would contain all the linestring records in a given table?

Answer 1

If you know before hand what is your polygon:

SELECT * from linetable WHERE ST_Intersects(linetable.the_geom,(SELECT the_geom from polytable where id='123'));

or

SELECT * FROM linetable WHERE ST_Intersects(linetable.the_geom, ST_GeomFromText('POLYGON((0 0,0 1,1 1,0 1,0 0))');

There are many ways to fetch the polygon you want, but the path is to try for ST_Intersects = true

OR do you need the polygon that encloses all linestrings?

For it you can use ConvexHull

http://postgis.refractions.net/docs/ST_ConvexHull.html