I want to delete a column from a table. I used FdoPropertyDefinition::Delete() function to mark the property to be deleted. But when i call ApplySchema::Execute() it throws an exception. exceptionString = "Schema public has errors; cannot apply it " and exceptionString "Column testdump.public.testtable.test14 has conditional rows or rows with non-null values, cannot delete its property ". I want to know to how to delete the all the entries of just one column so that i can drop that column.