mysql 预处理

DELIMITER $$
drop procedure if exists  touch_;
CREATE PROCEDURE `touch_`(IN a varchar(20),IN b varchar(20),IN c varchar(20))

BEGIN
SET  a ="3";
SET  b ="2";
SET  v ="1";

set @v_flag = concat("select * from t where id!=",a," and  id!=",b," and id!=",c);
prepare ee from @v_flag;
EXECUTE ee ;
DEALLOCATE PREPARE ee;
END$$
call touch_(‘1’,’2’,’3’);

存储过程只能在begin 和end 之间设置变量值