INSERT INTO  `ukrstal_db`.`category` (

`id` ,
`parent_id` ,
`rewrite` ,
`top` ,
`image` ,
`sort_order`
)
VALUES (
NULL ,  '0',  'category-1',  '1',  'sadasd',  '0'
)
Ответ MySQL: Документация

#1452 - Cannot add or update a child row: a foreign key constraint fails (`ukrstal_db`.`category`, CONSTRAINT `fk-category-parent_id-category-id` FOREIGN KEY (`parent_id`) REFERENCES `category` (`id`) ON DELETE CASCADE)