Question

我是postgreSQL的新手。我在postgreSQL数据库中导入了一个表。导入的表有一个＆＃39; geom＆＃39;字段（加密形式的坐标）。我正在使用以下查询

select ST_AsGeoJSON(geom) from dataTab where objectid='3'

我的坐标如下

"{"type":"MultiPolygon","coordinates":[[[[979999.082000002,196493.280000001],[979897.966399997,196147.8204],[979718.105800003,196197.441599995],[979823.056799993,196549.6884],[979999.082000002,196493.280000001]]]]}"

但是我要将这些数据绘制成地图，我需要将坐标作为下面的表格

[-73.9284914226121,40.5578463559797] - 具有WK ID的谷歌地图中的此坐标为4326

有人请帮我解决这个问题吗？

Answer 1

我很高兴地说我得到了上述问题的答案。

首先，我们需要找出表格的SRID。对于代码

下面的用法

 override func viewDidLoad() {
    super.viewDidLoad()
    self.getAllUsers()
    self.fetchData()
}
 func getAllUsers(){
    ref = Database.database().reference()
    ref.child("users").observe(.value, with: { (snapshot) in
        if let result = snapshot.children.allObjects as? [DataSnapshot] {
            for child in result {
                var userid = child.key
                print(userid)
                self.uuid.append(userid)
            }
        }
        if self.uuid.contains((Auth.auth().currentUser?.uid)!) {
            print("Id matched")
        }
    })

    let array = ["Frodo", "sam", "wise", "gamgee"]
    let randomIndex = Int(arc4random_uniform(UInt32(array.count)))
    print(array[randomIndex])

}
 func fetchData() {
    let randomIndex = Int(arc4random_uniform(UInt32(uuid.count)))
    print(uuid[randomIndex])
    print(randomIndex)
    randomI = randomIndex
    Message.downloadAllMessages(forUserID: uuid[randomIndex], completion: {[weak weakSelf = self] (message) in
        weakSelf?.items.append(message)
        weakSelf?.items.sort{ $0.timestamp < $1.timestamp }
        DispatchQueue.main.async {
            if let state = weakSelf?.items.isEmpty, state == false {
                weakSelf?.tableView.reloadData()
                weakSelf?.tableView.scrollToRow(at: IndexPath.init(row: self.items.count - 1, section: 0), at: .bottom, animated: false)
            }
        }
    })
    Message.markMessagesRead(forUserID: uuid[randomIndex])
}

如果是'0'，那就没问题了。在我的情况下，我的桌子的WELL-KNOWN IDENTIFIER是2263.

要获取与WELL-KNOWN IDENTIFIER 4326相对应的geom数据，请运行以下查询

SELECT ST_SRID(geom) FROM dataTab LIMIT 1;

以上查询的结果是

select st_asgeojson(st_transform(ST_SetSRID(geom, 2263), 4326)) AS geojson 
FROM  dataTab 
where objectid='3'

坐标不匹配。有没有办法找出相应的坐标？

1 个答案: