在一个数字串的每3个数字中添加一个常数。

Question

我尽力想为这个问题起一个更好的标题，但那是我能做出来的全部。好吧，我将尝试通过举例来解释它。假设我有。 Set x = 100200300; Set y = 10; BNow I want to add y into all first 3 numbers which is "100" then add it into "200" and so on. 我想知道我是否可以在循环中使用 "select left "函数来实现？不知道如何应用它，因此我在这里寻求帮助。请帮助我。祝福

DELIMITER $$
CREATE PROCEDURE proc(

)
BEGIN

    DECLARE counter INT DEFAULT 1;
    set @x = '100200300400';
    set @y = 10;
    WHILE counter <= @x DO
        select concat(substring(@x,counter,3) + @y,substring(@x,(counter +3),3) + @y) x;
    END WHILE;

END$$

DELIMITER ;

Answer 1

可能是

SET @X = 100200300;
SET @Y = 10;

select concat(substring(@x,1,3) + @y,substring(@x,4,3) + @y,substring(@x,7,3) + @y) x;

+-----------+
| x         |
+-----------+
| 110210310 |
+-----------+
1 row in set (0.001 sec)

如果x是未知长度，DROP PROCEDURE IF EXISTS P; DELIMITER $$ CREATE PROCEDURE p(

)
BEGIN

    DECLARE counter INT DEFAULT 1;
    set @x = '100200300400';
    set @y = 10;
    SET @OUT = '';
    L:WHILE counter <= @x / 3 DO
          #SELECT COUNTER;
          IF @x is null or COUNTER > 10 THEN LEAVE L; END IF;
          SET @OUT = CONCAT(@OUT,substring(@x,counter,3) + @y);
          SET @X = REPLACE(@X,@out,'');

        #select concat(substring(@x,counter,3) + @y,substring(@x,(counter +3),3) + @y) x;
        SET COUNTER = COUNTER + 3;

    END WHILE;
    select @out;
END $$

DELIMITER ;

CALL P();

DELIMITER ;