我正在尋找附近的地點的地理/空間搜索。我有這樣的半正矢查詢正在運行對一個表:選擇唯一記錄
SELECT
uid, adrLat, adrLng,
round(3956 * 2 * ASIN(SQRT(POWER(SIN((39.97780609 - abs(adrLat)) * pi()/180/2), 2) + COS(39.97780609 * pi()/180) * COS(abs(adrLat) * pi()/180) * POWER(SIN((-105.25861359 - adrLng) * pi()/180/2), 2))), 2) AS distance
FROM dataPoints
WHERE adrLng BETWEEN -105.2680699902 AND -105.2491571898
AND adrLat BETWEEN 39.970559713188 AND 39.985052466812
HAVING distance <= 0.30 and distance > 0.00
ORDER BY distance;
這給我一個結果,就像這樣:
+-----+-------------+---------------+----------+
| uid | adrLat | adrLng | distance |
+-----+-------------+---------------+----------+
| 191 | 39.97764587 | -105.25627136 | 0.12 |
| 520 | 39.97746658 | -105.25627136 | 0.13 |
| 265 | 39.97560120 | -105.25814056 | 0.15 |
| 266 | 39.97560120 | -105.25814056 | 0.15 |
| 274 | 39.97710037 | -105.25589752 | 0.15 |
| 98 | 39.97764969 | -105.26172638 | 0.17 |
| 576 | 39.97967911 | -105.25613403 | 0.18 |
| 575 | 39.97967911 | -105.25613403 | 0.18 |
| 469 | 39.97895813 | -105.25386810 | 0.26 |
| 470 | 39.97895813 | -105.25386810 | 0.26 |
| 1 | 39.98003006 | -105.25471497 | 0.26 |
| 383 | 39.97621155 | -105.26350403 | 0.28 |
| 431 | 39.97459793 | -105.25507355 | 0.29 |
| 430 | 39.97459793 | -105.25507355 | 0.29 |
| 429 | 39.97459793 | -105.25507355 | 0.29 |
| 428 | 39.97459793 | -105.25507355 | 0.29 |
+-----+-------------+---------------+----------+
然而,正如你可能會說,一些記錄在表中複製(這是數據提供給我的方式,我必須這樣保留它。)265:266,576:575,469:470和431-428都是重複的。
有沒有辦法修改查詢來選擇唯一記錄?它看起來像我必須匹配adrLat和adrLng來過濾重複項,但我不確定是否可以在同一個查詢中完成所有操作,或者如果我必須對結果進行一些後處理。
有沒有原因你不使用'SPATIAL'函數(和索引)? – Quassnoi 2010-11-01 21:14:58
是的,當這個項目開始時,我和其他開發者都不知道MySQL的空間支持。編碼Haversine公式是一件容易的事。也許下一個項目...... – KirAsh4 2010-11-02 05:31:25