text: CREATE TABLE tab_key1(
      id bigint NOT NULL auto_increment,
      PRIMARY KEY (id)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
  
  
  CREATE TABLE tab_problem (
    id bigint NOT NULL auto_increment,
    key1 bigint NOT NULL,
  
    PRIMARY KEY (id),
    UNIQUE (key1),
    CONSTRAINT `key1` FOREIGN KEY (key1) REFERENCES tab_key1(id)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
  