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PostgreSQL:
SELECT ST_DistanceSpheroid(pos, ST_SetSRID(ST_MakePoint(#{lon}, #{lat}), 4326), 'SPHEROID["WGS 84",6378137,298.257223563]') as distance
FROM parking_lot_table
WHERE
  ST_DistanceSpheroid(pos, ST_SetSRID(ST_MakePoint(#{lon}, #{lat}), 4326), 'SPHEROID["WGS 84",6378137,298.257223563]') < 5000 AND
  ORDER BY distance
LIMIT 1

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const geohash = require('ngeohash');

// 1. 將經緯度座標轉成Geohash
const taipei101Geohash = geohash.encode(25.03463, 121.56441)
console.log(taipei101Geohash); // wsqqqm2t2，默認層級九

// 2. 將Geohash轉成經緯度座標
const taipei101LatLon = geohash.decode(taipei101Geohash);
// Geohash轉回經緯度會有誤差
console.log(taipei101LatLon.latitude); // 25.034644603729248
console.log(taipei101LatLon.longitude); // 121.56442880630493

// 3. 找出Geohash周圍八個網格
const taipei101GeohashNeighbors = geohash.neighbors(taipei101Geohash)
console.log(taipei101GeohashNeighbors);
// wsqqqm2t2 周圍的八個geohash網格
// [
//     'wsqqqm2t8',
//     'wsqqqm2t9',
//     'wsqqqm2t3',
//     'wsqqqm2t1',
//     'wsqqqm2t0',
//     'wsqqqm2mp',
//     'wsqqqm2mr',
//     'wsqqqm2mx'
// ]

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const geohash = require('ngeohash');

const taipei101Geohash = geohash.encode(25.03463, 121.56441, 4)
console.log(taipei101Geohash); // wsqq, 取層級四

const taipei101GeohashNeighbors = geohash.neighbors(taipei101Geohash)
console.log(taipei101GeohashNeighbors);
// [
//   'wsqr', 'wsqx',
//   'wsqw', 'wsqt',
//   'wsqm', 'wsqj',
//   'wsqn', 'wsqp'
// ]

// 1. 找出周圍八個網格中指定位置的網格
const neighbor = geohash.neighbor(taipei101Geohash, [1,0])
console.log('neighbor = ', neighbor); // wsqr，最上面的八個網格

// 2. 找出Geohash網格周圍四個角落的經緯度
const bbox = geohash.decode_bbox('wsqq')
console.log(bbox); 
// 最小緯度、最小經度、最大緯度、最大經度
// [ 24.9609375, 121.2890625, 25.13671875, 121.640625 ]

// 3. 找出範圍內的所有geohash網格
// 切到的會算進去嗎？
const bboxes = geohash.bboxes(25.1, 121.6, 25.2, 121.7, 5)
console.log(bboxes);
// 找wsqq下層級五的geohash網格
// [
//   'wsqqz', 'wsqwb',
//   'wsqwc', 'wsqrp',
//   'wsqx0', 'wsqx1',
//   'wsqrr', 'wsqx2',
//   'wsqx3'
// ]