名稱
ST_GeomFromText — 從已知文本表示法 (WKT) 返回指定的 ST_Geometry 值。
概要
geometry ST_GeomFromText(text WKT);
geometry ST_GeomFromText(text WKT, integer srid);
描述
從 OGC 已知文本表示法構造 PostGIS ST_Geometry 物件。
![[Note]](../images/note.png)
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ST_GeomFromText 函數有兩種變體。第一種不採用 SRID，並返回一個沒有定義空間參考系統 (SRID=0) 的幾何物件。第二種採用 SRID 作為第二個參數，並返回一個將此 SRID 作為其元數據一部分的幾何物件。 |
此方法實作了 OGC 簡單功能 SQL 1.1 實作規範 s3.2.6.2 - 選項 SRID 來自一致性套件。
此方法實作了 SQL/MM 規範。SQL-MM 3: 5.1.40
此方法支援圓形字串和曲線。
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雖然不符合 OGC 標準，但 ST_MakePoint 比 ST_GeomFromText 和 ST_PointFromText 快。對於數值座標值，它也更容易使用。ST_Point 是另一個速度與 ST_MakePoint 相似的選項，並且符合 OGC 標準，但除了 2D 點之外，它不支援任何其他類型。 |
![[Warning]](../images/warning.png)
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變更：2.0.0 在舊版本的 PostGIS 中，允許 ST_GeomFromText('GEOMETRYCOLLECTION(EMPTY)')。為了更好地符合 SQL/MM 標準，這在 PostGIS 2.0.0 中現在是非法的。現在應該寫成 ST_GeomFromText('GEOMETRYCOLLECTION EMPTY') |
範例
SELECT ST_GeomFromText('LINESTRING(-71.160281 42.258729,-71.160837 42.259113,-71.161144 42.25932)');
SELECT ST_GeomFromText('LINESTRING(-71.160281 42.258729,-71.160837 42.259113,-71.161144 42.25932)',4269);
SELECT ST_GeomFromText('MULTILINESTRING((-71.160281 42.258729,-71.160837 42.259113,-71.161144 42.25932))');
SELECT ST_GeomFromText('POINT(-71.064544 42.28787)');
SELECT ST_GeomFromText('POLYGON((-71.1776585052917 42.3902909739571,-71.1776820268866 42.3903701743239,
-71.1776063012595 42.3903825660754,-71.1775826583081 42.3903033653531,-71.1776585052917 42.3902909739571))');
SELECT ST_GeomFromText('MULTIPOLYGON(((-71.1031880899493 42.3152774590236,
-71.1031627617667 42.3152960829043,-71.102923838298 42.3149156848307,
-71.1023097974109 42.3151969047397,-71.1019285062273 42.3147384934248,
-71.102505233663 42.3144722937587,-71.10277487471 42.3141658254797,
-71.103113945163 42.3142739188902,-71.10324876416 42.31402489987,
-71.1033002961013 42.3140393340215,-71.1033488797549 42.3139495090772,
-71.103396240451 42.3138632439557,-71.1041521907712 42.3141153348029,
-71.1041411411543 42.3141545014533,-71.1041287795912 42.3142114839058,
-71.1041188134329 42.3142693656241,-71.1041112482575 42.3143272556118,
-71.1041072845732 42.3143851580048,-71.1041057218871 42.3144430686681,
-71.1041065602059 42.3145009876017,-71.1041097995362 42.3145589148055,
-71.1041166403905 42.3146168544148,-71.1041258822717 42.3146748022936,
-71.1041375307579 42.3147318674446,-71.1041492906949 42.3147711126569,
-71.1041598612795 42.314808571739,-71.1042515013869 42.3151287620809,
-71.1041173835118 42.3150739481917,-71.1040809891419 42.3151344119048,
-71.1040438678912 42.3151191367447,-71.1040194562988 42.3151832057859,
-71.1038734225584 42.3151140942995,-71.1038446938243 42.3151006300338,
-71.1038315271889 42.315094347535,-71.1037393329282 42.315054824985,
-71.1035447555574 42.3152608696313,-71.1033436658644 42.3151648370544,
-71.1032580383161 42.3152269126061,-71.103223066939 42.3152517403219,
-71.1031880899493 42.3152774590236)),
((-71.1043632495873 42.315113108546,-71.1043583974082 42.3151211109857,
-71.1043443253471 42.3150676015829,-71.1043850704575 42.3150793250568,-71.1043632495873 42.315113108546)))',4326);
SELECT ST_GeomFromText('CIRCULARSTRING(220268 150415,220227 150505,220227 150406)');