Find location with in 1 mile in postgresql query

Question

I have 2 tables 1 is for facility and 1 is for customer. both contained latitude longitude we want query to fetch customer's available with in 1 miles of facility. We don't want to use postgres function like ST_Distance. Any alternate query to achieve it.

Answer 1

Iterate java list of location and used haversine formula to calculate distance in miles

    private double distance(double LatOne, double LonOne, double LatTwo, double LonTwo) {
        LonOne = Math.toRadians(LonOne);
        LonTwo = Math.toRadians(LonTwo);
        LatOne = Math.toRadians(LatOne);
        LatTwo = Math.toRadians(LatTwo);     
        double deltaLon = LonTwo - LonOne;
        double deltaLat = LatTwo - LatOne;
        double formula = Math.pow(Math.sin(deltaLat / 2), 2)+ Math.cos(LatOne) * Math.cos(LatTwo)* Math.pow(Math.sin(deltaLon / 2),2);
        double fOutput = 2 * Math.asin(Math.sqrt(formula));        
        return (fOutput * 3956) ;
    }