model 执行错误 [ 新手入门 ]

CDbCommand 无法执行 SQL 语句:

SQLSTATE[HY000]: General error: 1452 Cannot add or update a child row: a foreign key constraint fails (`blog`.`tbl_post`, CONSTRAINT `FK_post_author` FOREIGN KEY (`author_id`) REFERENCES `tbl_user` (`id`) ON DELETE CASCADE). The SQL statement executed was: INSERT INTO `tbl_post` (`title`, `content`, `tags`, `status`, `update_time`, `create_time`, `author_id`) VALUES (:yp0, :yp1, :yp2, :yp3, :yp4, :yp5, :yp6) 

请问这是什么问题啊