How do I convert a latitude/longitude pair into a PostGIS geography type?

Question

I\'m trying to load a bunch of latitude/longitude pairs into a PostGIS geography type so as to be able to query by location.

In particular I have a table with float lat

Answer 1

To perform exchange between lat and lng you may use:

update mytable set geography = ST_GeographyFromText('SRID=4326;POINT(' || st_x(geom) || ' ' ||  st_y(geom) || ')');

with or without srid.