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Tutorial Basis Data Spasial – Jenis Query Spasial

Ada banyak sekali Query Spatial diantaranya disebutkan sebagai berikut, beserta artinya:

Spatial Function Inspectors

Of which PostGIS type are you?

ST_GeometryType()

What is your srid?

ST_SRID()

Is this geometry a collection?

ST_isCollection() 

Are you a valid geometry?

ST_isValid() 

Are you an empty geometry?

ST_isEmpty() 

How many vertices do you have?

ST_nPoints() 

How many member geometries?

ST_NumGeometries(collection)

How many holes?

ST_NumInteriorrings(poly) 

What is the Nth geometry member?

ST_GeometryN(collection, N) 

What is your outer ring?

ST_ExteriorRing(poly) 

What is your Nth inner ring?

ST_InteriorRingN(poly, N) 

Where do you start?

ST_StartPoint(line)

Spatial Function Constructors

Make a point geometry

ST_MakePoint(x,y) 

Make a general geometry

ST_GeomFromText()

Make a polygon

ST_MakePolygon(closed_line) 

Make a bbox polygon

ST_MakeEnvelope()

Spatial Function Binary Comparisons

Do their bboxes overlap?

A && B 

Do they intersect?

ST_Intersects(A,B) 

Do they not intersect?

ST_Disjoint(A,B) 

Does A fully contain B?

ST_Contains(A,B)

Are they spatially equal?

ST_Equals(A,B) 

Do they touch?

ST_Touches(A,B) 

Do they overlap?

ST_Overlaps(A,B)

Materi Lengkap

Untuk memperdalam pemahaman mengenai Basis Data Spasial Menggunakan QGIS, berikut materi selengkapnya yang akan dibahas.


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