MySQL storage and custom functions

select col_name,
case when char_length(col_intro)>20 then
concat(left(col_intro,20),'.....')
else col_intro end
from tb_college;


drop function if exists truncate_string;
delimiter $
create function truncate_string(
content varchar(12000),
max_length int unsigned
)
returns varchar(12000) no sql
begin
declare result varchar(12000)default content;
	if char_length(content)>max_length then
			set result=concat(left(content,max_length),'.....');
	end if;
	return result;
end $
delimiter ;


select col_name,
truncate_string(col_intro,20)
from tb_college;

delimiter $
create procedure sp_upgrade_emp_sal()
begin
	start transaction;
	update tb_emp set sal=sal+100 where dno=10;
	update tb_emp set sal=sal+200 where dno=20;
	update tb_emp set sal=sal+300 where dno=30;
	commit;
end$
delimiter ;

call sp_upgrade_emp_sal();

delimiter $
create procedure sp_get_avg_sal(
in dept_no int,
out avg_sal decimal(10,2)
)begin
select round(avg(sal),2) into avg_sal
from tb_emp where dno=dept_no;
end $
delimiter ;

call sp_get_avg_sal(10,@sal);
select @sal;