### 26.3.36 The INFORMATION\_SCHEMA ST\_SPATIAL\_REFERENCE\_SYSTEMS Table

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 The [`ST_SPATIAL_REFERENCE_SYSTEMS`](information-schema-st-spatial-reference-systems-table.html) table provides information about available spatial reference systems (SRSs) for spatial data. This table is based on the SQL/MM (ISO/IEC 13249-3) standard.

 Entries in the [`ST_SPATIAL_REFERENCE_SYSTEMS`](information-schema-st-spatial-reference-systems-table.html) table are based on the [European Petroleum Survey Group](http://epsg.org) (EPSG) data set, except for SRID 0, which corresponds to a special SRS used in MySQL that represents an infinite flat Cartesian plane with no units assigned to its axes. For additional information about SRSs, see [Section 11.4.5, “Spatial Reference System Support”](spatial-reference-systems.html).

 The [`ST_SPATIAL_REFERENCE_SYSTEMS`](information-schema-st-spatial-reference-systems-table.html) table has these columns:

* `SRS_NAME`

   The spatial reference system name. This value is unique.

* `SRS_ID`

   The spatial reference system numeric ID. This value is unique.

  `SRS_ID` values represent the same kind of values as the SRID of geometry values or passed as the SRID argument to spatial functions. SRID 0 (the unitless Cartesian plane) is special. It is always a legal spatial reference system ID and can be used in any computations on spatial data that depend on SRID values.

* `ORGANIZATION`

   The name of the organization that defined the coordinate system on which the spatial reference system is based.

* `ORGANIZATION_COORDSYS_ID`

   The numeric ID given to the spatial reference system by the organization that defined it.

* `DEFINITION`

   The spatial reference system definition. `DEFINITION` values are WKT values, represented as specified in the [Open Geospatial Consortium](http://www.opengeospatial.org) document [OGC 12-063r5](http://docs.opengeospatial.org/is/12-063r5/12-063r5.html).

   SRS definition parsing occurs on demand when definitions are needed by GIS functions. Parsed definitions are stored in the data dictionary cache to enable reuse and avoid incurring parsing overhead for every statement that needs SRS information.

* `DESCRIPTION`

   The spatial reference system description.

#### Notes

* The `SRS_NAME`, `ORGANIZATION`, `ORGANIZATION_COORDSYS_ID`, and `DESCRIPTION` columns contain information that may be of interest to users, but they are not used by MySQL.

#### Example

```
mysql> SELECT * FROM ST_SPATIAL_REFERENCE_SYSTEMS
       WHERE SRS_ID = 4326\G
*************************** 1. row ***************************
                SRS_NAME: WGS 84
                  SRS_ID: 4326
            ORGANIZATION: EPSG
ORGANIZATION_COORDSYS_ID: 4326
              DEFINITION: GEOGCS["WGS 84",DATUM["World Geodetic System 1984",
                          SPHEROID["WGS 84",6378137,298.257223563,
                          AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],
                          PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],
                          UNIT["degree",0.017453292519943278,
                          AUTHORITY["EPSG","9122"]],
                          AXIS["Lat",NORTH],AXIS["Long",EAST],
                          AUTHORITY["EPSG","4326"]]
             DESCRIPTION:
```

 This entry describes the SRS used for GPS systems. It has a name (`SRS_NAME`) of WGS 84 and an ID (`SRS_ID`) of 4326, which is the ID used by the [European Petroleum Survey Group](http://epsg.org) (EPSG).

 The `DEFINITION` values for projected and geographic SRSs begin with `PROJCS` and `GEOGCS`, respectively. The definition for SRID 0 is special and has an empty `DEFINITION` value. The following query determines how many entries in the [`ST_SPATIAL_REFERENCE_SYSTEMS`](information-schema-st-spatial-reference-systems-table.html) table correspond to projected, geographic, and other SRSs, based on `DEFINITION` values:

```
mysql> SELECT
         COUNT(*),
         CASE LEFT(DEFINITION, 6)
           WHEN 'PROJCS' THEN 'Projected'
           WHEN 'GEOGCS' THEN 'Geographic'
           ELSE 'Other'
         END AS SRS_TYPE
       FROM INFORMATION_SCHEMA.ST_SPATIAL_REFERENCE_SYSTEMS
       GROUP BY SRS_TYPE;
+----------+------------+
| COUNT(*) | SRS_TYPE   |
+----------+------------+
|        1 | Other      |
|     4668 | Projected  |
|      483 | Geographic |
+----------+------------+
```

 To enable manipulation of SRS entries stored in the data dictionary, MySQL provides these SQL statements:

* [`CREATE SPATIAL REFERENCE SYSTEM`](create-spatial-reference-system.html): See [Section 13.1.19, “CREATE SPATIAL REFERENCE SYSTEM Statement”](create-spatial-reference-system.html). The description for this statement includes additional information about SRS components.

* [`DROP SPATIAL REFERENCE SYSTEM`](drop-spatial-reference-system.html): See [Section 13.1.31, “DROP SPATIAL REFERENCE SYSTEM Statement”](drop-spatial-reference-system.html).

