Postgres: How do I get the closest distance for each element within a point coordinate table from a polyline table? And if this is possible what version of Postgres is this doable.
In the absence of any further details on your tables, your best bet is to install PostGIS, which is the spatial-enablement extension to Postgresql. PostGIS 2 requires Postgresql 9.1 or higher. PostGIS 1.x will run on earlier versions of Postgresql but you might as well get the most up to date versions.
Then follow a few tutorials so you can cast your tables as GIS point and line features (unless they are already are like that - it's not clear from your post at the time of writing).
Once you have your data and PostGIS set up, use ST_Distance. You could skip the paragraph above and do it all in the ST_Distance sql command using one of the ST_GeomFromXXX (substitute format for XXX e.g. ST_GeomFromText) but that would mean a more complex SQL command (your call). Just be careful with your projections and coordinate systems (which is why a tutorial is useful if you're not familiar with GIS - which is what I am guessing from your query).