カテゴリ：: 地理空間関数

ST_MAKEPOLYGON , ST_POLYGON¶

Constructs a GEOGRAPHY or GEOGRAPHY object that represents a polygon without holes. The function uses the specified LineString as the outer loop.

こちらもご参照ください。: TO_GEOGRAPHY , TO_GEOMETRY

構文¶

ST_MAKEPOLYGON( <geography_or_geometry_expression> )

引数¶

geography_or_geometry_expression: A GEOGRAPHY or GEOMETRY object that represents a LineString in which the last point is the same as the first (i.e. a loop).

戻り値¶

The function returns a value of type GEOGRAPHY or GEOMETRY.

使用上の注意¶

The lines of the polygon must form a loop. Therefore, the last Point in the sequence of Points defining the LineString must be the same Point as the first Point in the sequence.
ST_POLYGON は、 ST_MAKEPOLYGON のエイリアスです。

For GEOMETRY objects, the returned GEOMETRY object has the same SRID as the input.

例¶

GEOGRAPHY Examples¶

これは、 ST_MAKEPOLYGON 関数の簡単な使用法を示しています。以下の一連のポイントは、幅1°、高さ2°の測地線矩形領域を定義し、ポリゴンの左下隅は赤道（緯度）とグリニッジ（経度）からはじまります。シーケンスの最後のポイントは、ループを完了する最初のポイントと同じです。

SELECT ST_MAKEPOLYGON(
   TO_GEOGRAPHY('LINESTRING(0.0 0.0, 1.0 0.0, 1.0 2.0, 0.0 2.0, 0.0 0.0)')
   ) AS polygon1;
+--------------------------------+
| POLYGON1                       |
|--------------------------------|
| POLYGON((0 0,1 0,1 2,0 2,0 0)) |
+--------------------------------+

GEOMETRY Examples¶

This shows a simple use of the ST_MAKEPOLYGON function.

SELECT ST_MAKEPOLYGON(
  TO_GEOMETRY('LINESTRING(0.0 0.0, 1.0 0.0, 1.0 2.0, 0.0 2.0, 0.0 0.0)')
  ) AS polygon;

+--------------------------------+
| POLYGON                        |
|--------------------------------|
| POLYGON((0 0,1 0,1 2,0 2,0 0)) |
+--------------------------------+

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