I am a new user to storing things GIS in PostgreSQL. My experience comes wholly from the QGIS training manual for 3.28.3 and some limited experience with QGIS.
I added the PostGIS extension to my database (address per the instructions). I then added geometry to the table called people. I started looking for where the CRS was stored and found a field in the VIEW called 'geometry_columns' called SRID. I looked at the data in this view for the people table. I discovered that the field is locked and uneditable. Further I discovered that the SQL attached to it did not allow inserts or updates. At this point I was quite confused.
I persisted and discovered that I could import a shapefile and did so, not knowing the CRS or SRID was set to 0. Again I tried to find a way to edit the entry in the database to no avail. I did load it as a new user I created.
I reimported when I discovered I had to assign a CRS even though the shapefile had an entry in it for that CRS. I then used the processing tools 'export to PostGreSQL' and it did store the SRID properly. I did the same with the layer created from the shapefile with 0 or the srid to a new layer in postgreSQL. Both the latter correctly stored the SRID.
Is there anyway to edit, after the fact, the srid stored in the geometry_columns view manually within pgAdmin? I am really unclear why the field was locked! And as a result was totally surprised to learn that I could send it to the database from QGIS. Perhaps the only way is to get it right the first time.
But there has got to be a way to unlock the srid even though it is in a view....I just don't know how to do it.