I didn't use the '-E 3857' switch when importing the OSM data into postgresql using osm2psql.
I'm trying to set up a map server for the first time and I'm following the instructions from here: https://github.com/mapserver/mapserver/wiki/RenderingOsmDataWindows#osm-prep.
I read that epsg900913 and epsg3857 are basically the same here: What is the difference between EPSG:900913 and EPSG:3857?.
How do I change/transform the spatial reference in the osm tables (i.e. osm_line, osm_point, osm_polygon, etc) within postgresql from epsg900913 to epsg3857 using a SQL command?