mysql多日志表结果集合拼接存储过程_MySQL

drop PROCEDURE if EXISTS unionSp;
DELIMITER //
create procedure unionSp(sTime varchar(32), eTime varchar(32),tchema varchar(32))

begin

declare sqlVar varchar(1024000);
declare rest int;
declare tableName varchar(1024);

set rest = 100;
set sqlVar='';

while rest > 0 do
 
 set sTime = (select DATE_FORMAT((select ADDDATE(sTime,1)),'%Y%m%d'));
 set tableName=CONCAT('tbl_req_',sTime);

 select count(1) from information_schema.tables where table_name = tableName and TABLE_SCHEMA=tchema into @cnt;
 if @cnt != 0 then

	if rest=1 then
	 set sqlVar=CONCAT(sqlVar,' SELECT DISTINCT channel_id,app_id from tbl_req_',sTime);
	ELSE
	 set sqlVar=CONCAT(sqlVar,' SELECT DISTINCT channel_id,app_id from tbl_req_',sTime,' UNION');
	END IF;

END if;

set rest = DATEDIFF(eTime,sTime);

END while;

set @v_s=sqlVar;
prepare stmt from @v_s;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;


end;

// 
DELIMITER;

call unionSp('20140730','20140930','biz_date')