A geographic coordinate pair has an order: ST_GEOGPOINT(longitude, latitude). Swapping the numbers can create a valid point in the wrong part of the world, so a successful query doesn't prove the location is right. This lesson uses original fictional delivery points near a fixed depot. They are coordinate exercises, not customer addresses.
ST_DISTANCE(a, b) returns the shortest geographic distance in meters. ST_DWITHIN(a, b, 3000) tests whether that distance is within a 3,000-meter radius. Use the same units in the requirement and the SQL. A straight geographic distance doesn't account for roads, river crossings or traffic and mustn't be labeled driving distance.
The console implements point-to-point spherical distance and radius checks. BigQuery supports many more geography shapes and functions; polygons, routing and spatial indexing aren't simulated here. Round reported distances only after calculating them. Filtering a rounded distance can shift a boundary.