mysql - Operand should contain 1 column(s) stored procedure -

i trying use multiple select @ 1 procedure assign value of variable. got error "operand should contain 1 column(s)" code :

delimiter $$  drop procedure if exists `bankdb`.`charge` $$ create procedure `bankdb`.`charge` () begin   declare idcust_val int;   declare balance_val float;   declare balance_val1 float;   declare balance_val2 float;   declare productcd_val varchar(10);   declare producttype_val varchar(10);   declare no_more_rows int default 0;   declare num_rows int default 0;    declare col_cur cursor   select a.cust_id, a.avail_balance, a.product_cd, p.product_type_cd   account a, product p    a.product_cd = p.product_cd;   declare continue handler not found set no_more_rows = 1;    open col_cur;   select found_rows() num_rows;    read_loop: loop   if no_more_rows   close col_cur;   leave read_loop;   end if;   fetch col_cur idcust_val, balance_val, productcd_val, producttype_val;   select idcust_val, balance_val, productcd_val;     if producttype_val = 'account'       if productcd_val = 'sav' || productcd_val = 'cd'         if balance_val < 2000               select (balance_val-10) balance_val;         end if;       else         select (balance_val+(balance_val*0,05)) balance_val;       end if;      else       select (balance_val-(balance_val*0,1)) balance_val;     end if;   /*update account set avail_balance = balance_val account_id = idcust_val;*/   end loop read_loop; end $$ delimiter ; 

please help!

change decimal point ',' '.'

0,05 -> 0.05 0,1 - 0.1