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我正在尝试组合一个查询来查找图中节点 2 公里范围内的节点。假设我有一个数据集，它标记了纳斯卡线条中的一些地理符号：

Name,Latitude,Longitude
Hummingbird,-14.692131,-75.148892
Monkey,-14.706940,-75.138532
Condor,-14.697444,-75.126208
Spider,-14.694145,-75.122381
Spiral,-14.688277,-75.122746
Hands,-14.694459,-75.113881
Tree,-14.693898,-75.114520
Astronaut,-14.745222,-75.079755
Dog,-14.706401,-75.130788
Wing,-14.680309,-75.100385
Parrot,-14.689463,-75.107498

我有一个使用以下方法创建的空间索引：

CREATE INDEX GeoGlyph.index.Location 
ON GeoGlyph(Latitude,Longitude) SPATIAL ENGINE LUCENE

现在，我想找到“手”字形 2 公里内的节点，我可以通过手动输入纬度/经度坐标来输入此查询：

SELECT Name, Latitude, Longitude, $distance AS Distance 
FROM GeoGlyph 
WHERE [Latitude,Longitude,$spatial] 
NEAR [-14.694459,-75.113884,{"maxDistance":2}] 
ORDER BY Distance

我得到结果： 

+----+------+----------+----------+--------------------+
|#   |Name  |Latitude  |Longitude |Distance            |
+----+------+----------+----------+--------------------+
|0   |Hands |-14.694459|-75.113884|5.230883384236603E-6|   
|1   |Tree  |-14.693897|-75.11446 |0.08836486627516459 |
|2   |Spider|-14.694363|-75.12358 |1.0442063409276094  |
|3   |Spiral|-14.688309|-75.12276 |1.1754176535538237  |
|4   |Condor|-14.698346|-75.128334|1.6149944044266815  |
+----+------+----------+----------+--------------------+

到目前为止，一切都很好。

由于输入坐标有点麻烦，我宁愿使用名称字段“Hands”查找 2 公里内的字形。

这是我目前陷入困境的地方。我想我应该能够使用LET 块来获得我想要的东西......但到目前为止我尝试过的东西不起作用：

SELECT *,$distance AS Distance 
FROM GeoGlyph 
LET $temp = (SELECT * FROM GeoGlyph WHERE Name = "Hands")
WHERE [Latitude,Longitude,$spatial] 
NEAR [$temp.Latitude, $temp.Longitude,{"maxDistance":2}] 
ORDER BY Distance

有什么建议么？

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1 回答 1

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我想出了办法……如果可以安全地假设该字段GeoGlyph.Name是唯一的，我可以first()在 NEAR 子句中使用：

SELECT *,$distance AS Distance 
FROM GeoGlyph 
LET $temp = (SELECT * FROM GeoGlyph WHERE Name = "Hands")
WHERE [Latitude,Longitude,$spatial] 
NEAR [first($temp).Latitude, first($temp).Longitude,{"maxDistance":2}] 
ORDER BY Distance

这似乎奏效了。

orientdb {db=nazca.orientdb}> SELECT *,$distance AS Distance FROM GeoGlyph LET $temp = (SELECT * FROM GeoGlyph WHERE Name = "Hands") WHERE [Latitude,Longitude,$spatial] NEAR [first($temp).Latitude, first($temp).Longitude,{"maxDistance":2}] ORDER BY Distance

+----+-----+--------+----------+----------+------+-------------------+
|#   |@RID |@CLASS  |Latitude  |Longitude |Name  |Distance           |
+----+-----+--------+----------+----------+------+-------------------+
|0   |#25:5|GeoGlyph|-14.694459|-75.113884|Hands |0.0                |
|1   |#25:6|GeoGlyph|-14.693897|-75.11446 |Tree  |0.08836394983673491|
|2   |#25:3|GeoGlyph|-14.694363|-75.12358 |Spider|1.0442092937404572 |
|3   |#25:4|GeoGlyph|-14.688309|-75.12276 |Spiral|1.1754175925032648 |
|4   |#25:2|GeoGlyph|-14.698346|-75.128334|Condor|1.614998440581846  |
+----+-----+--------+----------+----------+------+-------------------+

如果我不能依赖该Name领域的独特性，我仍然不确定我将如何做到这一点。例如，如果我想计算彼此相距 2 公里内的所有地理符号对......

于 2016-12-05T18:09:22.780 回答