How to import height and depth data into the database?

Question

Geolocation

I found a fresh srtm 1 arc-second resolution , that is, for every 30 meters there is global data (not only for the USA). But, like previous versions, it is limited to 50 degrees in latitude.
What alternative data are there with greater accuracy than GTOPO30 , which both for the oceans and for the rest of the land unreachable for srtm is only calculated for 30 arc-second - 1 km ?
In the case of solving the previous question, you will need the following: importing data into the database (it seems MySQL will do?) in the form of a table with a height value and lat/long. In general, in such a way that you can find the average height between any nearby points. Right approach?

Answer 1

There are no other, free, global, accurate data. So you don't need a database;)
Well, in general, the approach is strange. If your distances are small, then the average height is approximately equal to one of the points. If the distances are large, then why high accuracy?