MySQL触发器自动从DOB计算年龄并创建年龄字段插入数据

Question

DELIMITER $$

CREATE TRIGGER example
     BEFORE INSERT ON dates FOR EACH ROW
     BEGIN
     declare age int;
          IF ((set age = AND (select * , year(curdate())-year(dob) ) < 18)
          THEN
               CALL `'Cannot add or update row: only one active row allowed per type'`;
          END IF;
     END;
$$