Question

我有一个roadfollowing表，其中包含列

COLUMN geom geometry(LineString,4326);

我还有一个sub_polygon表，其中包含一列

COLUMN geom geometry(MultiPolygon,4326);

我想从存储在sub_polygon表中的线串中减去roadfollowing中存储的多边形，并使用这些新数据更新表。

我尝试执行以下查询：

WITH RESULTS as (
SELECT ST_Difference(public.roadnetwork.geom, public.sub_polygon.geom)
FROM public.roadnetwork, public.sub_polygon
),

 FILTERED_RESULTS as (
  SELECT RESULTS.st_difference FROM RESULTS where GeometryType(RESULTS.st_difference) <> 'GEOMETRYCOLLECTION'
)
 UPDATE public.roadnetwork
 SET geom = FILTERED_RESULTS.st_difference
 FROM FILTERED_RESULTS;

但我收到以下错误：

ERROR: Geometry type (MultiLineString) does not match column type (LineString)

我修改了查询以便以字符串格式检查结果：

WITH RESULTS as (
SELECT ST_Difference(public.roadnetwork.geom, public.sub_polygon.geom)
FROM public.roadnetwork, public.sub_polygon
),

 FILTERED_RESULTS as (
  SELECT ST_AsText(RESULTS.st_difference) FROM RESULTS where GeometryType(RESULTS.st_difference) <> 'GEOMETRYCOLLECTION'
)

SELECT * from FILTERED_RESULTS;

我可以看到结果中有一些MULTILINESTRING，无法在roadnetwork.geom列中复制，因为数据不一致：

...
MULTILINESTRING((51.5054201 25.3462475,51.505411 25.3462656,51.5052981 25.3464467,51.5051894 25.3466039,51.5049763 25.3469023,51.5048058 25.347141,51.5046538 25.347324,51.5044476 25.3475493,51.5041983 25.3478035,51.5038722 25.3481104,51.5035605 25.3483885,51.509695 25.3489269,51.5026179 25.3492445,51.5022888 25.349556),(51.5022888 25.349556,51.5022898 25.3495551),(51.5022888 25.349556,51.5017303 25.3500517))
LINESTRING(51.5017303 25.3500517,51.5014725 25.3502989,51.5013472 25.3504121)
LINESTRING(51.5013472 25.3504121,51.501175 25.3505679)
...

如何更新我的查询以便将MULTILINESTRING转换为LINESTRING，以便我可以成功更新我的表格？

Answer 1

您可以使用st_dump将MultiLineStrings扩展为LineStrings。

像这样的东西

public class FcmMessagingService extends FirebaseMessagingService {

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);

        String title = remoteMessage.getNotification().getTitle();
        final String message = remoteMessage.getNotification().getBody();



        if (title.contains("Added")) {
            Handler handler = new Handler(Looper.getMainLooper());
            handler.post(
                    new Runnable() {
                        @Override
                        public void run() {

                            Log.d("webUrl",""+MainActivity.mWebview.getUrl());

                            if(MainActivity.mWebview.getUrl().contains("http://example.com")) {
                                Toast.makeText(FcmMessagingService.this, message, Toast.LENGTH_SHORT).show();
                                MainActivity.reLoad();
                            }
                            }
                    }
            );

     }else{
            Intent intent = new Intent(this, MainActivity.class);
            intent.putExtra("value", "kh");
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_ONE_SHOT);
            Uri sounduri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
            NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this);
            notificationBuilder.setContentTitle(title);
            notificationBuilder.setContentText(message);
            notificationBuilder.setSmallIcon(R.mipmap.ic_icon);
            notificationBuilder.setSound(sounduri);
            notificationBuilder.setAutoCancel(true);
            notificationBuilder.setContentIntent(pendingIntent);
            NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

            notificationManager.cancel(0);
            notificationManager.notify(0, notificationBuilder.build());


        }


    }


}

在查询结果中将MULTILINESTRING转换为LINESTRING

1 个答案: