MySQL:
ST_LONGFROMGEOHASH
ST_LongFromGeoHash(geohash_str)
Returns the longitude from a geohash string value, as a
double-precision number in the range [?180, 180].
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().
ST_LongFromGeoHash() handles its arguments as described in the
introduction to this section.
URL: https://dev.mysql.com/doc/refman/8.0/en/spatial-geohash-functions.html
Example
mysql> SELECT ST_LongFromGeoHash(ST_GeoHash(45,-20,10));
+-------------------------------------------+
| ST_LongFromGeoHash(ST_GeoHash(45,-20,10)) |
+-------------------------------------------+
| 45 |
+-------------------------------------------+