mysql中的递归

drop function if exists getName;
create FUNCTION getName(v_code int) returns varchar(10)
begin 

    declare v_name varchar(10);
    declare v_name2 varchar(10);

    set v_name=‘‘;
    set v_name2=‘‘;
    
    repeat
        select `name`,`parent_code` into v_name,v_code from material_type where `code` = v_code limit 1;
        set v_name2 = concat_ws(‘/‘,v_name,v_name2);
    until v_code = 0 end repeat;    
    
    return v_name2;
    
end;

select  code,name,parent_code,getName(code) from material_type;