违反完整性约束：1452无法添加或更新子行：?mysql

我试图在我的注释表中插入值，但出现错误。俗话说，我不能添加或更新子行，我也不知道这意味着什么。

我的架构看起来像这样

-- Table structure for comments

DROP TABLE IF EXISTS comments; CREATE TABLE comments ( id varchar(36) NOT NULL, project_id varchar(36) NOT NULL, user_id varchar(36) NOT NULL, task_id varchar(36) NOT NULL, data_type_id varchar(36) NOT NULL, data_path varchar(255) DEFAULT NULL, message longtext, created datetime DEFAULT NULL, modified datetime DEFAULT NULL, PRIMARY KEY (id), KEY fk_comments_users (user_id), KEY fk_comments_projects1 (project_id), KEY fk_comments_data_types1 (data_type_id), CONSTRAINT fk_comments_data_types1 FOREIGN KEY (data_type_id) REFERENCES data_types (id) ON DELETE NO ACTION ON UPDATE NO ACTION, CONSTRAINT fk_comments_projects1 FOREIGN KEY (project_id) REFERENCES projects (id) ON DELETE NO ACTION ON UPDATE NO ACTION, CONSTRAINT fk_comments_users FOREIGN KEY (user_id) REFERENCES users (id) ON DELETE NO ACTION ON UPDATE NO ACTION ) ENGINE=InnoDB DEFAULT CHARSET=utf32;

-- Records of comments

-- Table structure for projects

DROP TABLE IF EXISTS projects; CREATE TABLE projects ( id varchar(36) NOT NULL, user_id varchar(36) NOT NULL, title varchar(45) DEFAULT NULL, description longtext, created datetime DEFAULT NULL, modified datetime DEFAULT NULL, PRIMARY KEY (id), KEY fk_projects_users1 (user_id), CONSTRAINT fk_projects_users1 FOREIGN KEY (user_id) REFERENCES users (id) ON DELETE NO ACTION ON UPDATE NO ACTION ) ENGINE=InnoDB DEFAULT CHARSET=utf32;

-- Records of projects

INSERT INTO projects VALUES ('50dcbc72-3410-4596-8b71-0e80ae7aaee3', '50dcbc5c-d684-40bf-9715-0becae7aaee3', 'Brand New Project', 'This is a brand new project', '2012-12-27 15:24:02', '2012-12-27 15:24:02'); 和我试图做的mysql语句看起来像这样

INSERT INTO anthonyl_fbpj.comments (project_id, user_id, task_id, data_type_id, message, modified, created, id) VALUES ('50dc845a-83e4-4db3-8705-5432ae7aaee3', '50dcbc5c-d684-40bf-9715-0becae7aaee3', '1', '50d32e5c-abdc-491a-a0ef-25d84e9f49a8', 'this is a test', '2012-12-27 19:20:46', '2012-12-27 19:20:46', '50dcf3ee-8bf4-4685-aa45-4eb4ae7aaee3') 我得到的错误看起来像这样

SQLSTATE [23000]：违反完整性约束：1452无法添加或更新子行：外键约束失败（anthonyl_fbpj。comments，CONSTRAINT fk_comments_projects1 FOREIGN KEY（project_id）引用projects（id）删除无操作，更新无操作）