Обьясните почему не работает constraint

sqlite> create table flags (
   ...>     id INTEGER,
   ...>     name VARCHAR NOT NULL,
   ...>     descr VARCHAR DEFAULT NULL,
   ...>     type_id INTEGER NOT NULL,
   ...>     live INTEGER NOT NULL DEFAULT 1,
   ...>     package_id INTEGER DEFAULT NULL,
   ...>     FOREIGN KEY (type_id) REFERENCES flag_types(id),
   ...>     FOREIGN KEY (package_id) REFERENCES packages(id),
   ...>     CONSTRAINT idx1_unq UNIQUE (name, descr, package_id),
   ...>     PRIMARY KEY (id)
   ...> );
sqlite> 
sqlite> select * from flags where name='x86' limit 2;
7647|x86||1|0|
7648|x86||1|0|
sqlite> select package_id from flags where name='x86' limit 2;


sqlite> select count(id) from flags where descr is NULL and name='x86' and package_id is NUll;
598
sqlite>