Question

Trigger actually. But how do i make this in mysql-workbench. So that anytime i have any new records in table1 it creates a new record referencing table1.id to table2.parentid ?

--- [OK] --- This is created
CREATE  TABLE IF NOT EXISTS `test`.`table1` (
  `id` BIGINT(20) NOT NULL AUTO_INCREMENT ,
  `name` VARCHAR(45) NULL ,
  PRIMARY KEY (`id`) )
ENGINE = InnoDB

--- [FAIL] --- #1005 - Can't create table 'test.table2' (errno: 150)
CREATE  TABLE IF NOT EXISTS `test`.`table2` (
  `id` BIGINT(20) NOT NULL AUTO_INCREMENT ,
  `parentid` VARCHAR(45) NULL ,
  `table1_id` BIGINT(20) NOT NULL ,
  PRIMARY KEY (`id`) ,
  INDEX `fk_table2_table1` (`parentid` ASC) ,
  CONSTRAINT `fk_table2_table1`
    FOREIGN KEY (`parentid` )
    REFERENCES `test`.`table1` (`id` )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB

Follow up:

1) Mysql workbench do not offer that

2) Click the table1 > click the triggers tab bottom > write

-- trigger module initiate
DELIMITER $$
CREATE TRIGGER triggertest1 BEFORE INSERT ON table1
  FOR EACH ROW BEGIN
    INSERT INTO table2 SET parentid = NEW.id; 
  END;
$$
DELIMITER ; --- return to normal

Answer 1

Thats because you have different datatype of id column in your child table change it to BIGINT(20)