How to check for absence of null column constraint in oracle sql?

Question

How to check if a column in a table has a null constraint in oracle db? Can this be verified using a data dictionary?

Answer 1

SELECT nullable FROM all_tab_cols WHERE owner = <<owner of table>> AND table_name = <<name of table>> AND column_name = <<name of column>> 

will work if the column is marked NOT NULL, and not, say, with a CHECK constraint, which checks that it is not NULL.