ST_LongFromGeoHash(geohash_str)

Returns the longitude from a geohash string value, as a DOUBLE value in
the range [−180, 180].

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

The remarks in the description of ST_LatFromGeoHash() regarding the
maximum number of characters processed from the geohash_str argument
also apply to ST_LongFromGeoHash().

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

