It took me a lot to discover but there is it is. Totally proved. I'm using MariaDB, and phalcon 2.0 x64 VC11. I stuck with it when trying to insert a new row in tableB inside a model of tableA. ID of tableB(child) is a foreign key to ID of table A(father). If there's any NOT NULL with a default value column in the table it will just do nothing(no error, no warning...but no insert as well). It happends with phql and also with ORM.