DROP SPATIAL REFERENCE SYSTEM [IF EXISTS] srid srid: 32-bit unsigned integer
DROP SPATIAL REFERENCE SYSTEM 4120;
If no SRS definition with the SRID value exists, an error occurs
IF EXISTS is specified. In that case, a
warning occurs rather than an error.
If the SRID value is used by some column in an existing table, an error occurs. For example:
mysql> DROP SPATIAL REFERENCE SYSTEM 4326; ERROR 3716 (SR005): Can't modify SRID 4326. There is at least one column depending on it.
To identify which column or columns use the SRID, use this query:
SELECT * FROM INFORMATION_SCHEMA.ST_GEOMETRY_COLUMNS WHERE SRS_ID=4326;
SRID values must be in the range of 32-bit unsigned integers, with these restrictions:
SRID 0 is a valid SRID but cannot be used with
DROP SPATIAL REFERENCE SYSTEM.
If the value is in a reserved SRID range, a warning occurs. Reserved ranges are [0, 32767] (reserved by EPSG), [60,000,000, 69,999,999] (reserved by EPSG), and [2,000,000,000, 2,147,483,647] (reserved by MySQL). EPSG stands for the European Petroleum Survey Group.
Users should not drop SRSs with SRIDs in the reserved ranges. If system-installed SRSs are dropped, the SRS definitions may be recreated for MySQL upgrades.