mysql - Unable to call a stored procedure -

i'm learning mysql stored procedures and, turns out, i'm not @ now. want create stored procedure selects columns different tables and, obviously, outputs result. have:

use `usertable159`; drop procedure if exists `getdatafor`;  delimiter $$ use `usertable159`$$ create definer=`michael`@`%` procedure `getdatafor`(in country varchar(2), in asin varchar(20),in fc varchar(1)) begin       set @sql = "select p.price, p.sku, p.fulfillment_channel, group_concat(es.excludedseller) excluded, r.excludenonfeatured        "+country+"_products p       left join ("+country+"_excludedsellers es, "+country+"_excluderules r)       on p.seller_sku = es.seller_sku , p.seller_sku = r.seller_sku p.asin = '" + asin + "' , p.fulfillment_channel = " + fc + "; ";        prepare stmt @sql;       execute stmt;       deallocate prepare stmt; end $$  delimiter ; 

from errors expected when writing this... 1 surprising me:

error code: 1054. unknown column 'de' in 'field list'

this how call it:

call getdatafor(de, b000lnhb8a, 2); 

the in parameter country not in selected columns, how come?

i tried calling with

call getdatafor('de', 'b000lnhb8a', '2'); 

which results in

error code: 1064. have error in sql syntax; check manual corresponds mysql server version right syntax use near '2' @ line 1

you have several problems:

1) cannot concatenate strings + in mysql. must use concat() built-in function.

2) left join syntax incorrect. should left join x on ... left join y on ....

3) must quote arguments. looks tried that. need that.