Table of Contents
After populating spatial columns with values, you are ready to query and analyze them. MySQL provides a set of functions to perform various operations on spatial data. These functions can be grouped into four major categories according to the type of operation they perform:
Functions that convert geometries between various formats
Functions that provide access to qualitative or quantitative properties of a geometry
Functions that describe relations between two geometries
Functions that create new geometries from existing ones
Spatial analysis functions can be used in many contexts, such as:
Any interactive SQL program, like mysql or MySQLCC
Application programs written in any language that supports a MySQL client API
MySQL supports the following functions for converting geometry values between internal format and either WKT or WKB format:
GeomFromText(wkt[,srid]) | Converts a string value from its WKT representation into internal geometry format and returns the result. A number of type-specific functions are also supported, such as PointFromText() and LineFromText(); see GIS WKT Functions. |
GeomFromWKB(wkb[,srid]) | Converts a binary value from its WKB representation into internal geometry format and returns the result. A number of type-specific functions are also supported, such as PointFromWKB() and LineFromWKB(); see GIS WKB Functions. |
AsText(g) |
Converts a value in internal geometry format to its WKT representation
and returns the resulting string.
mysql> SET @g = 'LineString(1 1,2 2,3 3)'; mysql> SELECT AsText(GeomFromText(@g)); +--------------------------+ | AsText(GeomFromText(@G)) | +--------------------------+ | LINESTRING(1 1,2 2,3 3) | +--------------------------+ |
AsBinary(g) | Converts a value in internal geometry format to its WKB representation and returns the resulting binary value. |