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地理空間関数

ST_AREA

Returns the area of the Polygon(s) in a GEOGRAPHY or GEOMETRY object.

構文

ST_AREA( <geography_or_geometry_expression> )

引数

geography_expression

The argument must be of type GEOGRAPHY or GEOMETRY.

戻り値

Returns a REAL value, which represents the area:

  • For GEOGRAPHY input values, the area is in square meters.

  • For GEOMETRY input values, the area is computed with the same units used to define the input coordinates.

使用上の注意

  • geography_expression がポリゴン、 MultiPolygon、またはポリゴンを含む GeometryCollection でない場合、 ST_AREA は0を返します。

  • geography_expression が GeometryCollection の場合、 ST_AREA はコレクション内のポリゴンの面積の合計を返します。

GEOGRAPHY Examples

This uses the ST_AREA function with GEOGRAPHY objects to calculate the area of Earth's surface 1 degree on each side with the bottom of the area on the equator:

SELECT ST_AREA(TO_GEOGRAPHY('POLYGON((0 0, 1 0, 1 1, 0 1, 0 0))')) AS area;
+------------------+
|             AREA |
|------------------|
| 12364036567.0764 |
+------------------+

GEOMETRY Examples

The following example calls the ST_AREA function with GEOMETRY objects that represent a Point, LineString, and Polygon.

SELECT ST_AREA(g), ST_ASWKT(g)
FROM (SELECT TO_GEOMETRY(column1) as g
  from values ('POINT(1 1)'),
              ('LINESTRING(0 0, 1 1)'),
              ('POLYGON((0 0, 0 1, 1 1, 1 0, 0 0))'));
+------------+--------------------------------+
| ST_AREA(G) | ST_ASWKT(G)                    |
|------------+--------------------------------|
|          0 | POINT(1 1)                     |
|          0 | LINESTRING(0 0,1 1)            |
|          1 | POLYGON((0 0,0 1,1 1,1 0,0 0)) |
+------------+--------------------------------+
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