Table schema:
CREATE TABLE table_name_31 (geohash_length INTEGER, lng_error VARCHAR, lng_bits VARCHAR)

Question: What is the highest geohash length when there is a ng error of ±0.00017, and a lng bits smaller than 20?
SQL: SELECT MAX(geohash_length) FROM table_name_31 WHERE lng_error = "±0.00017" AND lng_bits < 20