Spatial data types and operations which are supported in the MSQL are mostly based upon the Open Geospatial Consortium's OpenGIS - Simple Features Common Architecture and OpenGIS - Simple Features SQL specifications, although they don't follow the standard in every detail, but depart from it in several ways.

Two main differences of MSQL compared to the OpenGIS specification are:

1. MSQL supports only 2-dimensional spatial types.
2. There is no single GEOMETRY type which can contain arbitrary spatial features.

Spatial objects are strongly-typed, i.e. they are always of a specialized data type, (e.g. point, linestring, polygon) and many spatial functions accept just the arguments of a specific type (e.g. ST_Length accepts only (multi)linestring objects).

A list of all the available spatial functions which deal with values of spatial types can be found here.

Spatial Coordinate Systems

There are two different kinds of spatial types available, depending on the coordinate system they rely on:

• Geometric types - for representing spatial features in a planar coordinate system (i.e. x, y coordinates on an Euclidean plane).
• Geographic types - for representing spatial features in a geodetic coordinate system (i.e. latitude/longitude coordinates on a sphere or an ellipse).

The coordinates of all geometric objects are assumed to be in the Mireo World-Point coordinate system.
This is a coordinate system based on the Web Mercator projection (a.k.a. Google Web Mercator), but all the coordinates are scaled to fit into int32 data type.

The coordinates of all geographic objects are assumed to be in the WGS 84 coordinate system.
This is the World Geodetic System, the spatial reference system used in the GPS navigation system.

Conversions between geometric and geographic types are possible using ST_TOGEOG and ST_TOGEOM built-in functions. Conversions between the Mireo World-Point coordinates and the more common WGS 84 longitude-latitude coordinates are possible using the functions TO_LON, TO_LAT, TO_WPX, TO_WPY.

SINGLE GEOMETRIES

Single 2D spatial objects in the Euclidean plane (point, line, polygon).

Name	Description	Example	Example (WKT)
point	A 2-D point in space		POINT (30 10)
line	An arbitrary 2-D polyline, can be open or closed, can intersect with itself		LINESTRING (30 10, 10 30, 40 40)
polygon	An arbitrary 2-D polygon, can have holes		POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))

GEOMETRY COLLECTIONS

Collections of 2D spatial objects in the Euclidean plane (mpoint, mline, mpolygon).

Name	Description	Example	Example (WKT)
mpoint	A set of any number of 2-D points, can be empty or contain one element		MULTIPOINT ((10 40), (40 30), (20 20), (30 10))
mline	A set of any number of 2-D linestrings, can be empty or contain one element		MULTILINESTRING ((10 10, 20 20, 10 40), (40 40, 30 30, 40 20, 30 10))
mpolygon	A set of any number of 2-D polygons, can be empty or contain one element		MULTIPOLYGON (((30 20, 45 40, 10 40, 30 20)), ((15 5, 40 10, 10 20, 5 10, 15 5)))

SINGLE GEOGRAPHIES

Single 2D spatial objects on a geodetic sphere (gpoint, gline, gpolygon).

Name	Description	Example	Example (WKT)
gpoint	A 2-D point in geodetic space		POINT (30 10)
gline	An arbitrary 2-D polyline, can be open or closed, can intersect with itself		LINESTRING (30 10, 10 30, 40 40)
gpolygon	An arbitrary 2-D polygon, can have holes		POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))

GEOGRAPHY COLLECTIONS

Collections of 2D spatial objects on a geodetic sphere (gmpoint, gmline, gmpolygon).

Name	Description	Example	Example (WKT)
gmpoint	A set of any number of 2-D points, can be empty or contain one element		MULTIPOINT ((10 40), (40 30), (20 20), (30 10))
gmline	A set of any number of 2-D linestrings, can be empty or contain one element		MULTILINESTRING ((10 10, 20 20, 10 40), (40 40, 30 30, 40 20, 30 10))
gmpolygon	A set of any number of 2-D polygons, can be empty or contain one element		MULTIPOLYGON (((30 20, 45 40, 10 40, 30 20)), ((15 5, 40 10, 10 20, 5 10, 15 5)))

WKT Representation

The OpenGIS standard defines a Well-Known Text format for representing spatial objects as human-readable character strings. MSQL supports the WKT format by providing built-in functions for parsing and outputting WKT representations of its spatial objects. For a full list of these functions, see the documentation on spatial conversion functions.

The Well-Known Text format is defined according to the following rules:

Basic WKT building blocks:

<coord>            ::= floating-point literal, e.g. '10' or '-3.5' or '1.3e6'
<coord-pair>       ::= <coord> <coord>
<coord-sequence>   ::= '(' <coord-pair> [',' <coord-pair>]* ')'
<point>            ::= '(' <coord-pair> ')'
<point-sequence>   ::= '(' <point> [',' <point>]* ')'
<polygon-rings>    ::= '(' <coord-sequence> [',' <coord-sequence>]* ')'

WKT representations of spatial objects:

<point-WKT>           ::= 'POINT' <point>
<linestring-WKT>      ::= 'LINESTRING' ( <coord-sequence> | 'EMPTY' )
<polygon-WKT>         ::= 'POLYGON' ( <polygon-rings> | 'EMPTY' )
<multipoint-WKT>      ::= 'MULTIPOINT' ( <coord-sequence> | <point-sequence> | 'EMPTY' )
<multilinestring-WKT> ::= 'MULTILINESTRING' ( '(' <coord-sequence> [',' <coord-sequence>]* ')' | 'EMPTY' )
<multipolygon-WKT>    ::= 'MULTIPOLYGON' ( '(' <polygon-rings> [',' <polygon-rings>]* ')' | 'EMPTY' )

Several examples of valid WKT strings:

'POINT (10 20)'
'LINESTRING (10 20, 30 30, 50 10)'
'POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0), (3 3, 7 3, 5 5, 3 3))'
'MULTIPOINT (10 10, 30 30)'
'MULTILINESTRING ((0 0, 100 100), (110 110, 10 10))'
'MULTIPOLYGON EMPTY'

The WKT format is used to define MSQL spatial literals. It is also assumed as the default textual representation for casting spatial objects to and from character strings.

WKB Representation