Example of simple Gaia query:

    SELECT *
    FROM gaiadr1.gaia_source
    WHERE parallax >= 15 AND parallax <=50
    AND phot_g_mean_mag >= 9 and phot_g_mean_mag<=9.5

which yields a total of 1626 stars.  

  Useful fields are
    - ra        (deg)
    - dec       (deg)
    - parallax  (mas)
    - parallax_error (mas)
    - phot_g_mean_mag 
    - l (deg) (galactic longitude)
    - b (deg) (galactic latitude)

1635378410781933568
	
3062945825380755840

Here's an example of one of my queries


SELECT g.ra, g.dec, g.parallax, g.parallax_error, g.phot_g_mean_mag, s.sdssdr9_oid, sv.g_mag, sv.i_mag
FROM gaiadr1.gaia_source as g
  JOIN gaiadr1.sdss_dr9_best_neighbour as s
    ON g.source_id = s.source_id
  JOIN gaiadr1.sdssdr9_original_valid as sv
    ON s.sdssdr9_oid = sv.sdssdr9_oid
WHERE  g.ra > 120 and g.ra < 130 and g.dec > 0 and g.dec < 5
       and g.parallax > 0 and g.parallax_error > 0