如何将几何图形与geojson统一

Question

我想用geojson与postgis统一我的几何图形，但它不起的作用

select ST_AsGeoJSON(ST_Union(geo)) from (       
select ST_Buffer(ST_Transform(geom,4326)::geography,500)::geometry as geo FROM table_data
Union all
select ST_Buffer(ST_Transform(ST_GeomFromGeoJSON('{"type":"Polygon","coordinates":[[[4.7718133999999983,45.751034700379336],[4.7732161999999985,45.753077900379047],[4.7801820999999993,45.754600200378832],[4.7821356999999995,45.754461600378846],[4.7820908999999983,45.756529400378554],[4.7852063999999981,45.758854600378235],[4.7870810999999991,45.765387900377306],[4.7892927999999992,45.766544300377156],[4.7905733999999986,45.767903400376952],[4.7912280999999988,45.771446600376443],[4.7924920999999987,45.773515700376151],[4.795157399999999,45.775803000375831],[4.7921674999999988,45.779246400375342],[4.7909021999999979,45.7822510003749],[4.7921700999999981,45.785207500374476],[4.7919013999999995,45.786570700374284],[4.7857526999999989,45.78585010037439],[4.7849289999999982,45.788069200374082],[4.7883277999999985,45.789775100373831],[4.7905100999999988,45.79089470037367],[4.7934197999999979,45.789282500373886],[4.7975291999999987,45.789847200373806],[4.7971985999999989,45.791482600373584],[4.8013753999999986,45.791290000373614],[4.8022111999999995,45.792041100373517],[4.8070630999999988,45.789003600373945],[4.8096090999999985,45.792440400373437],[4.8139945999999991,45.7942379003732],[4.816270799999999,45.7970563003728],[4.8166826999999994,45.798412100372595],[4.8184066999999988,45.79930800037247],[4.8196049999999984,45.799385500372459],[4.8203043999999995,45.802155100372055],[4.823837499999998,45.802009300372085],[4.8241582999999979,45.804528900371722],[4.827171599999998,45.804712700371695],[4.8321631999999983,45.806999500371354],[4.8322759999999985,45.805557200371574],[4.8345430999999985,45.804307100371751],[4.8369834999999979,45.808262800371182],[4.8389672999999993,45.803852500371804],[4.8412469999999983,45.803216700371905],[4.8405863999999994,45.801963500372075],[4.8371177999999979,45.798335300372614],[4.8335112999999978,45.796853900372838],[4.8291917999999994,45.796213900372919],[4.8225897999999985,45.792472100373438],[4.8189186999999993,45.789726100373841],[4.8223407999999992,45.787745800374125],[4.8235941999999978,45.7843982003746],[4.8331413999999988,45.781757600374981],[4.8381035999999975,45.782485600374869],[4.8412973999999993,45.779434900375307],[4.843032499999997,45.778919000375382],[4.8456883999999993,45.782278300374905],[4.8480465999999982,45.7843718003746],[4.8512447999999981,45.786034900374361],[4.8553270999999993,45.787138700374207],[4.8598280999999979,45.787021300374228],[4.8586979999999986,45.777832200375535],[4.8583621999999984,45.7724259003763],[4.8611271999999985,45.771875100376384],[4.8630206999999981,45.769191400376755],[4.8653019999999989,45.768296700376887],[4.8680070999999989,45.766351800377159],[4.8718481999999979,45.761265000377911],[4.8744195999999986,45.760525100378004],[4.8737345999999988,45.758743700378254],[4.8765671999999993,45.758236600378311],[4.8760987999999976,45.75532090037872],[4.8832563999999987,45.754329400378872],[4.8935626999999995,45.753986900378919],[4.8983773999999993,45.752922300379076],[4.8972099999999994,45.75020600037945],[4.8966669999999981,45.747279000379848],[4.894829999999998,45.743669000380365],[4.8897088999999969,45.735086900381567],[4.8877978999999989,45.730775400382178],[4.8867335999999986,45.729315100382379],[4.8870075999999978,45.726124800382827],[4.8875538999999995,45.720357300383625],[4.8860551999999986,45.721490600383468],[4.8808419999999986,45.721734600383414],[4.8623578999999983,45.726914700382714],[4.8598145999999973,45.730704900382186],[4.8536965999999984,45.729738900382323],[4.854488599999998,45.718893100383831],[4.849740999999999,45.718796500383839],[4.837449799999999,45.718613000383861],[4.8381020999999986,45.713631300384556],[4.8404877999999982,45.707959700385359],[4.8376821999999988,45.707366600385427],[4.8330493999999984,45.709996800385049],[4.828008699999998,45.711609300384836],[4.8237961999999994,45.714307600384458],[4.8224713999999995,45.715919700384241],[4.8209415999999985,45.7190690003838],[4.8202529999999983,45.720487800383616],[4.8186822999999981,45.726595700382759],[4.817820499999999,45.726491900382776],[4.816876699999999,45.730396400382212],[4.8147679999999982,45.731819900382021],[4.8141234999999982,45.733487300381782],[4.8130294999999981,45.739802800380915],[4.8135772999999995,45.743391600380406],[4.8161482999999983,45.74727460037986],[4.8183329999999991,45.749075700379606],[4.814626099999999,45.749650600379532],[4.813400399999999,45.748004800379753],[4.8025329999999986,45.75167040037924],[4.7995818999999988,45.7505287003794],[4.7945228999999978,45.749232600379592],[4.7835874999999994,45.744245600380275],[4.778781399999998,45.747540400379812],[4.7775823999999991,45.747168900379876],[4.7755830999999986,45.74810970037975],[4.7718133999999983,45.751034700379336]]]}'),4326)::geography,0)::geometry as geo) t

但是我有这个错误

输入几何体具有未知(0(SRID

Answer 1

table_data.geom中的一些几何图形没有声明的投影，因此无法重新投影它们。

您首先必须设置当前投影(在下面的示例中为3857(，然后才能对其进行转换

select st_transform('point(0 0)',4326);
--> ERROR:  ST_Transform: Input geometry has unknown (0) SRID
select st_transform(ST_SetSRID('point(0 0)'::geometry,3857),4326);
--> 0101000020E610000000000000000000000000000000000000

或者，您可以修改表格以强制每个几何体具有相同的投影：doc