ST_GeomCollFromText — Makes a collection Geometry from collection WKT with the given SRID. If SRID is not given, it defaults to 0.
geometry ST_GeomCollFromText(text  WKT, integer  srid);
geometry ST_GeomCollFromText(text  WKT);
Makes a collection Geometry from the Well-Known-Text (WKT) representation with the given SRID. If SRID is not given, it defaults to 0.
OGC SPEC 3.2.6.2 - option SRID is from the conformance suite
Returns null if the WKT is not a GEOMETRYCOLLECTION
                 
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                 If you are absolutely sure all your WKT geometries are collections, don't use this function. It is slower than ST_GeomFromText since it adds an additional validation step.  | 
            
            
            This method implements the OGC Simple Features
            Implementation Specification for SQL 1.1.
         s3.2.6.2
            
            This method implements the SQL/MM specification.
        
SELECT ST_GeomCollFromText('GEOMETRYCOLLECTION(POINT(1 2),LINESTRING(1 2, 3 4))');