Table schema:
CREATE TABLE table_name_99 (geohash_length INTEGER, lat_error VARCHAR, lat_bits VARCHAR)

Question: What is the highest geohash length when the lat error is ±0.00068, and the lat bits larger than 17?
SQL: SELECT MAX(geohash_length) FROM table_name_99 WHERE lat_error = "±0.00068" AND lat_bits > 17