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Explore miscellaneous GIS functions in MariaDB Server. This section details various SQL functions that support geographic information system operations and spatial data analysis.
Generate a Geohash string from a point or coordinates. This function encodes spatial locations into short, alphanumeric strings for efficient indexing and proximity searches.
Returns the geohash corresponding to the input values, or NULL if any argument is NULL. Geohashes encode latitude and longitude coordinates into a text string made up only of numeric and lowercase latin letter characters.
The longitude parameter is a numeric value in the interval [180, -180]. latitude is a numeric value in the interval [90, -90].
In the case of point, the x coordinate is treated as the latitude and the y coordinate is treated as the latitude. The same constraints apply.
The max_length parameter is the upper limit on the resulting string size and cannot exceed 100.
The function decodes a given geohash and returns the latitude.
This page is licensed: CC BY-SA / Gnu FDL
ST_GeoHash(longitude, latitude, max_length)
ST_GeoHash(point, max_length)SELECT ST_GeoHash(ST_GeomFromText('POINT(1 1)'),15), ST_GeoHash(0,30,15);
+----------------------------------------------+---------------------+
| ST_GeoHash(ST_GeomFromText('POINT(1 1)'),15) | ST_GeoHash(0,30,15) |
+----------------------------------------------+---------------------+
| s00twy01mtw037m | sj248j248j248j2 |
+----------------------------------------------+---------------------+Decode a Geohash to retrieve the longitude. This function returns the longitude coordinate (X-axis) from a given Geohash string.
Decodes a given geohash string and returns the longitude in the interval [180, -180].
If the argument is NULL, the return value is NULL. If the argument is invalid, an ER_INCORRECT_TYPE error is thrown.
The function can be used to generate geohashes.
This page is licensed: CC BY-SA / Gnu FDL
Check if a geometry is valid. This function returns 1 if the geometry complies with OGC specifications (e.g., no self-intersections), 0 otherwise.
Given a geometry input, returns 1 if the argument is geometrically valid according to the OGC specifications, 0 if the argument is not geometrically valid.
Unlike , requires valid GIS data, or ERROR 3037 (22023): Invalid GIS data provided to function st_isvalid is returned.
A requires both x and y co-ordinates:
This page is licensed: CC BY-SA / Gnu FDL
Decode a Geohash to retrieve the latitude. This function returns the latitude coordinate (Y-axis) from a given Geohash string.
ST_LatFromGeoHash(geohash)Decodes a given geohash string and returns the latitude in the interval [90, -90].
If the argument is NULL, the return value is NULL. If the argument is invalid, an ER_INCORRECT_TYPE error is thrown.
The function can be used to generate geohashes.
This page is licensed: CC BY-SA / Gnu FDL
Simplify a geometry using the Douglas-Peucker algorithm. This function reduces the number of vertices in a geometry while preserving its general shape, useful for rendering maps.
Takes as input a geometry (g) and a double (max_distance). It applies the on g and returns the resulting geometry.
The goal of the Douglas-Peucker algorithm is to provide generalized simplifications by returning a geometry that is similar to g but uses only a subset of points. To perform the simplification, all the vertices that are shorter than max_distance are removed.
The algorithm may produce self-intersections and therefore result in invalid geometries. can be used to test validity of the result.
If the max_distance is not positive or is NULL, an ER_WRONG_ARGUMENT will occur.
This page is licensed: CC BY-SA / Gnu FDL
ST_LongFromGeoHash(geohash)ST_IsValid(g)ST_Simplify(g, max_distance)ST_Collect is an aggregate function that can also be used as a window function.
Given multiple geometries, returns the aggregation of the distinct geometry arguments. This function also supports the DISTINCT option. If DISTINCT is used, it returns the aggregation of the distinct geometry arguments.
The resulting value type is chosen using the following policy:
If all arguments are Point values, the result is a MultiPoint value.
If all arguments are LineString values, the result is a MultiLineString value.
If all arguments are Polygon values, the result is a MultiPolygon value.
Otherwise, the result is a GeometryCollection value.
If there are multiple geometry arguments and those arguments are in the same spatial reference system (SRS), the return value is in that SRS. If those arguments are not in the same SRS, an ER_GIS_DIFFERENT_SRIDS_AGGREGATION error occurs.
Multiple Point geometries aggregated into a MultiPoint geometry:
This page is licensed: CC BY-SA / Gnu FDL
ST_Collect(g)CREATE OR REPLACE TABLE t1 ( running_number INTEGER NOT NULL
AUTO_INCREMENT, grouping_condition INTEGER, location GEOMETRY , PRIMARY KEY (
running_number));
INSERT INTO t1 ( grouping_condition, location ) VALUES
( 0,ST_GEOMFROMTEXT('POINT(0 0)',4326)),
( 1,ST_GEOMFROMTEXT('POINT(0 0)',4326)),
( 0,ST_GEOMFROMTEXT('POINT(1 0)',4326)),
( 1,ST_GEOMFROMTEXT('POINT(2 0)',4326)),
( 0,ST_GEOMFROMTEXT('POINT(3 0)',4326));
SELECT ST_EQUALS( (SELECT ST_COLLECT( location ) AS t FROM t1),
ST_GEOMFROMTEXT('MULTIPOINT(0 0,0 0,1 0,2 0,3 0) ',4326)) AS equals;
+--------+
| equals |
+--------+
| 1 |
+--------+SELECT ST_LongFromGeoHash('zzzzzzzzz'), ST_LongFromGeoHash('sj248j248j248j2');
+---------------------------------+---------------------------------------+
| ST_LongFromGeoHash('zzzzzzzzz') | ST_LongFromGeoHash('sj248j248j248j2') |
+---------------------------------+---------------------------------------+
| 180 | 0 |
+---------------------------------+---------------------------------------+SELECT ST_IsValid(ST_GeomFromText('LINESTRING (0 0, 1 1)'));
+------------------------------------------------------+
| ST_IsValid(ST_GeomFromText('LINESTRING (0 0, 1 1)')) |
+------------------------------------------------------+
| 1 |
+------------------------------------------------------+
SELECT ST_IsValid(ST_GeomFromText('LINESTRING (0 0, 0 0)'));
+------------------------------------------------------+
| ST_IsValid(ST_GeomFromText('LINESTRING (0 0, 0 0)')) |
+------------------------------------------------------+
| 0 |
+------------------------------------------------------+SELECT ST_IsValid(ST_GeomFromText('POINT (0)'));
ERROR 3037 (22023): Invalid GIS data provided to function st_isvalid.SELECT ST_LatFromGeoHash('zzzzzzzzz'), ST_LatFromGeoHash('xvrfxvrfxvrfxvr');
+--------------------------------+--------------------------------------+
| ST_LatFromGeoHash('zzzzzzzzz') | ST_LatFromGeoHash('xvrfxvrfxvrfxvr') |
+--------------------------------+--------------------------------------+
| 90 | 30 |
+--------------------------------+--------------------------------------+SELECT ST_AsText(ST_Simplify(ST_GeomFromText('LINESTRING(0 0,0 2,2 2,2 4,4 4,4 6,6 6)'), 0.5));
+-----------------------------------------------------------------------------------------+
| ST_AsText(ST_Simplify(ST_GeomFromText('LINESTRING(0 0,0 2,2 2,2 4,4 4,4 6,6 6)'), 0.5)) |
+-----------------------------------------------------------------------------------------+
| LINESTRING(0 0,0 2,2 2,2 4,4 4,4 6,6 6) |
+-----------------------------------------------------------------------------------------+
SELECT ST_AsText(ST_Simplify(ST_GeomFromText('LINESTRING(0 0,0 2,2 2,2 4,4 4,4 6,6 6)'), 1));
+---------------------------------------------------------------------------------------+
| ST_AsText(ST_Simplify(ST_GeomFromText('LINESTRING(0 0,0 2,2 2,2 4,4 4,4 6,6 6)'), 1)) |
+---------------------------------------------------------------------------------------+
| LINESTRING(0 0,0 2,2 2,2 4,6 6) |
+---------------------------------------------------------------------------------------+Create a Point geometry from a Geohash. This function decodes a Geohash string into a Point object representing the location's center.
ST_PointFromGeoHash(geohash, srid)Takes a given geohash string and returns a point where the x is the longitude and the y is the latitude.
The latitude is returned as a numeric value in the interval [180, -180]. The longitude is returned as a numeric value in the interval [90, -90]. If the argument is NULL, the return value is NULL. If the argument is invalid, an ER_GIS_INVALID_DATA is thrown.
This page is licensed: CC BY-SA / Gnu FDL
SELECT ST_ASTEXT(ST_POINTFROMGEOHASH("s00twy01mtw037m",0));
+-----------------------------------------------------+
| ST_ASTEXT(ST_POINTFROMGEOHASH("s00twy01mtw037m",0)) |
+-----------------------------------------------------+
| POINT(1 1) |
+-----------------------------------------------------+
SELECT ST_ASTEXT(ST_POINTFROMGEOHASH(ST_GEOHASH(180,90,20),0));
+---------------------------------------------------------+
| ST_ASTEXT(ST_POINTFROMGEOHASH(ST_GEOHASH(180,90,20),0)) |
+---------------------------------------------------------+
| POINT(180 90) |
+---------------------------------------------------------+Validate and optionally return a geometry. This function checks if a geometry is valid according to OGC rules; it returns the geometry if valid, or NULL if not.
The function checks that a given geometry is compliant with the Well-Known Binary (WKB) format and Spatial Reference System Identifier (SRID) syntax, and is geometrically valid.
It returns the geometry if it's valid, or NULL if not.
The function is useful to filter out invalid geometry data.
A requires both x and y co-ordinates:
This page is licensed: CC BY-SA / Gnu FDL
ST_Validate(g)SELECT ST_ASTEXT(ST_VALIDATE(ST_GeomFromText('POINT(1 0)')));
+-------------------------------------------------------+
| ST_ASTEXT(ST_VALIDATE(ST_GeomFromText('POINT(1 0)'))) |
+-------------------------------------------------------+
| POINT(1 0) |
+-------------------------------------------------------+
SELECT ST_ASTEXT(ST_VALIDATE(ST_GeomFromText('POINT(1)')));
+-----------------------------------------------------+
| ST_ASTEXT(ST_VALIDATE(ST_GeomFromText('POINT(1)'))) |
+-----------------------------------------------------+
| NULL |
+-----------------------------------------------------+