DROP statistics_type 

if an association is defined with statistics_type, the command fails, otherwise the type is dropped 

DROP statistics_type FORCE

calls DISASSOCIATE FORCE for all objects associated with the statistics_type; drops statistics_type 

DROP object

calls DISASSOCIATE, drops object_type if DISASSOCIATE succeeds 

ALTER TABLE DROP COLUMN

if association is present for the column, this calls DISASSOCIATE FORCE with column; if no entry in ASSOCIATION$ but there are entries in type USATS$, then ODCIStatsDelete for the columns is invoked 

DISASSOCIATE

if user-defined statistics collected with the statistics type are present, the command fails 

DISASSOCIATE FORCE

deletes the entry in ASSOCIATION$ and calls ODCIStatsDelete 

ANALYZE TABLE DELETE 
STATISICS

the ODCIStatsDelete function is invoked; if any errors are raised, ANALYZE fails and the error is reported 

ASSOCIATE

if an association or user-defined statistics are present for the associated object, the command fails