MySQL数据库从身份证字段截取生日

id_card_no 身份证  birthday 生日  表名 basic_info

UPDATE basic_info SET birthday = STR_TO_DATE(CONCAT(SUBSTRING(id_card_no,7,4),'-',SUBSTRING(id_card_no,11,2),'-',SUBSTRING(id_card_no,13,2),' 00:00:00'),'%Y-%m-%d %H:%i:%s') WHERE birthday is NULL AND LENGTH(id_card_no) = 18;