DocumentDB - 如何在查询的SELECT部分​​返回距离？

Question

我想返回我的搜索坐标与我搜索的字段之间的距离。

例如，你可以使用这个＆＃34;查询游乐场＆＃34;： https://www.documentdb.com/sql/demo#geospatial

他们使用以下示例查询：

-- Find all volcanoes of type Stratovolcano
-- (http://www.sciencedaily.com/terms/stratovolcano.htm) 
-- that are within 100 km of Redmond, WA. 
SELECT *
FROM volcanoes v
WHERE ST_DISTANCE(v.Location, { 
    "type": "Point", 
    "coordinates": [-122.19, 47.36] 
    }) < 100 * 1000
AND v.Type = "Stratovolcano"
AND v["Last Known Eruption"] = "Last known eruption from 1800-1899, inclusive"

他们得到以下结果：

{
  "Volcano Name": "Rainier",
  "Country": "United States",
  "Region": "US-Washington",
  "Location": {
    "type": "Point",
    "coordinates": [
      -121.758,
      46.87
    ]
  },
  "Elevation": 4392,
  "Type": "Stratovolcano",
  "Status": "Dendrochronology",
  "Last Known Eruption": "Last known eruption from 1800-1899, inclusive",
  "id": "33eff74b-e331-bca5-bf32-f8ece733465a",
  "_rid": "FX8tANMM6QEeBAAAAAAAAA==",
  "_ts": 1438994836,
  "_self": "dbs/FX8tAA==/colls/FX8tANMM6QE=/docs/FX8tANMM6QEeBAAAAAAAAA==/",
  "_etag": "\"00008304-0000-0000-0000-55c551940000\"",
  "_attachments": "attachments/"
}

让我们说我希望在火山（[-121.758, 46.87]）和搜索坐标[-122.19, 47.36]之间的距离以米为单位

我的T-SQL开发人员说我可以从ST_DISTANCE子句中取出整个WHERE位，并将其与SELECT一起包括在内：

-- Find all volcanoes of type Stratovolcano
-- (http://www.sciencedaily.com/terms/stratovolcano.htm) 
-- that are within 100 km of Redmond, WA. 
SELECT *, ST_DISTANCE(v.Location, { 
    "type": "Point", 
    "coordinates": [-122.19, 47.36] 
    })
FROM volcanoes v
WHERE ST_DISTANCE(v.Location, { 
    "type": "Point", 
    "coordinates": [-122.19, 47.36] 
    }) < 100 * 1000
AND v.Type = "Stratovolcano"
AND v["Last Known Eruption"] = "Last known eruption from 1800-1899, inclusive"

然而，这不起作用，它只是给我一个语法错误：

{
  "errors": [
    {
      "severity": "Error",
      "location": {
        "start": 153,
        "end": 154
      },
      "code": "SC1001",
      "message": "Syntax error, incorrect syntax near ','."
    }
  ]
}

我尝试了一系列事情，例如v.*，将ST_DISTANCE的结果与AS别名，但我没有到达任何地方而且我＆＃ 39;我没有在谷歌找到我需要的东西。

那我该怎么办？对我来说，在一定距离内查询是至关重要的，但如果我必须重新计算客户端的所有距离，那么它的使用是有限的。

Answer 1

查询必须使用SELECT v, ST_DISTANCE(...)代替SELECT *, ST_DISTANCE(...)。与ANSI-SQL类似，DocumentDB中的SELECT子句可以包含值列表或使用*，但不能同时使用两者。

完整查询：

-- Find all volcanoes of type Stratovolcano
-- (http://www.sciencedaily.com/terms/stratovolcano.htm) 
-- that are within 100 km of Redmond, WA. 
SELECT v, ST_DISTANCE(v.Location, { 
    "type": "Point", 
    "coordinates": [-122.19, 47.36] 
    }) AS DistanceMetres
FROM volcanoes v
WHERE ST_DISTANCE(v.Location, { 
    "type": "Point", 
    "coordinates": [-122.19, 47.36] 
    }) < 100 * 1000
AND v.Type = "Stratovolcano"
AND v["Last Known Eruption"] = "Last known eruption from 1800-1899, inclusive"