How to store a row's multiple column's sum on that same table's same row's another column? [duplicate]

问题

CREATE TABLE `student`

(
  `student_id` int(5) NOT NULL AUTO_INCREMENT,
  `student_first_name` varchar(30) not null,
  `student_lase_name` varchar(30) not null,
  `student_roll_no` int(5) not null,
  `student_class` int(2) not null,
  PRIMARY KEY (`student_id`)
);

CREATE TABLE `result_sheet`
(
  `student_id` int(5),
  `student_first_name` varchar(30),
  `student_lase_name` varchar(30),
  `student_roll_no` int(5),
  `student_class` int(2),
  `mid_1_english` int(2),
  `mid_2_english` int(2),
  `mid_1_mathematics` int(2),
  `mid_2_mathematics` int(2),
  `mid_english` int(2),
  `mid_mathematics` int(2),
  `semester_final_english` int(2),
  `semester_final_mathematics` int(2),
  `total_english` int(2),
  `total_mathematics` int(2),
  `total` int(3),
   foreign key (student_id) references student(student_id) on delete cascade
);

delimiter $$
create trigger result_sheet_insert_trigger

after insert on student
for each row 
begin 
insert into result_sheet(student_id, student_first_name, student_lase_name, student_roll_no, student_class, mid_1_english, mid_2_english, mid_1_mathematics, mid_2_mathematics, mid_english, mid_mathematics, semester_final_english, semester_final_mathematics, total_english, total_mathematics, total)
values (new.student_id, new.student_first_name, new.student_lase_name, new.student_roll_no, new.student_class, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

end$$
delimiter ;

I want to store the avg of mid_1_english & mid_2_english on mid english for each row. How am I supposed to do that? Suppose I have 12 as mid_1_english and 20 as mid_2_english. Then I want to store 16 as mid english on result_sheet table.

回答1:

Try this:

UPDATE result_sheet SET mid_english = (mid_1_english + mid_2_english) / 2

来源：https://stackoverflow.com/questions/50790423/how-to-store-a-rows-multiple-columns-sum-on-that-same-tables-same-rows-anoth

标签

mysql

rdbms