mysql sql 拼接用法

create procedure proc_mc_drop_partition(in v_tablename varchar(50),v_interval int)
begin
	start TRANSACTION;
	set @s=CONCAT('alter table ',v_tablename,' drop partition ', CONCAT('p',DATE_FORMAT(DATE_SUB(now(),INTERVAL v_interval DAY),'%Y%m%d')));
	select @s;
	prepare stmt from @s;
	execute stmt;
	DEALLOCATE prepare stmt;
	COMMIT;
end