ST_LatFromGeoHash(geohash_str)

Returns the latitude from a geohash string value, as a DOUBLE value in
the range [−90, 90].

If the argument is NULL, the return value is NULL. If the argument is
invalid, an error occurs.

The ST_LatFromGeoHash() decoding function reads no more than 433
characters from the geohash_str argument. That represents the upper
limit on information in the internal representation of coordinate
values. Characters past the 433rd are ignored, even if they are
otherwise illegal and produce an error.

URL: https://dev.mysql.com/doc/refman/5.7/en/spatial-geohash-functions.html

