mysql存储过程调试方法

CREATE PROCEDURE `p_next_id`(kind_name VARCHAR(30), i_length int,currentSeqNo VARCHAR(3),OUT o_result INT)
BEGIN
     SET @a= NULL;
     SET @b= NULL;
     SELECT id INTO @a FROM t_seq WHERE number= currentSeqNo and length= i_length ;     
     IF (@a is null ) THEN
            select min(id) into @a FROM t_seq where length = i_length;
            select number  INTO @b FROM t_seq WHERE id = @a;ELSE
        select number  INTO @b FROM t_seq WHERE id = @a+1;        
     END IF;        
     SELECT @b INTO o_result;     
END

CREATE PROCEDURE `p_next_id`(kind_name VARCHAR(30), i_length int,currentSeqNo VARCHAR(3),OUT o_result INT)
BEGIN
     SET @a= NULL;
     SET @b= NULL;
     SELECT id INTO @a FROM t_seq WHERE number= currentSeqNo and length= i_length ;
---------注意该语句----------
 　　SELECT @a;     
----------------------------
     IF (@a is null ) THEN
            select min(id) into @a FROM t_seq where length = i_length;
            select number  INTO @b FROM t_seq WHERE id = @a;
---------注意该语句----------
       select @b;
----------------------------
     ELSE
        select number  INTO @b FROM t_seq WHERE id = @a+1;        
     END IF;        
     SELECT @b INTO o_result;     
END