Oracle Spatail Special Storage architecture

MDSYS.CS_SRS-----The table defines the name of the coordinate system and its ID values in Oracle spatial, which are all published by Open-gis. The currently defined coordinate system has reached 1018.

Mdsys. Sdo_angle_units-----This table defines the angle units, respectively, Degree,gon,grad,minute,radian,second

Mdsys. Sdo_dist_units-----The table defines the unit of distance. For example Km,m, there are 27 kinds of distance units.

Mdsys. Sdo_datums-----The table defines the commonly used geoid, such as WGS84, which defines 118 kinds of geoid.

Mdsys. Sdo_ellipsoids-----This table defines the commonly used ellipsoid, such as Krassovsky, which is defined in a total of 47.

Mdsys. Sdo_projections-----The table defines commonly used map projections, such as Mercator projection, geographic projection, and a total of 42 projection types.

Wktext Format:-----wktext field value is OpenGIS the description of the space coordinate system. If the user fixed the coordinate system, it must be defined strictly according to the format, you can use the function Sdo_cs. Validate_wkt to verify that the defined coordinate system conforms to the format.