I'm trying to use the SQL search at https://skyserver.sdss.org/dr18/SearchTools/sql to find (for example) QSOs with accurate redshifts from the SDSS. My query will look something like this:
SELECT TOP 100000
p.ra,p.dec,p.u,p.g,p.r,p.i,p.z,
s.specobjid, s.class, s.z as redshift
FROM PhotoObj AS p
JOIN SpecObj AS s ON s.bestobjid = p.objid
WHERE
p.e_z < 0.01
which gives me an error "Invalid column name 'e_z'. How can I find the names of the columns? I can't find them on the SDSS website?