mysql - 如何从Mysql中分离字符？

Question

我使用下面的例子:

select '10+20+30'

并产生值(value):

'++'

In other words, strip any digit and leave only signs.

Answer 1

功能:

DROP FUNCTION IF EXISTS getMOps;
DELIMITER $$
CREATE FUNCTION getMOps
(   s varchar(100)
)
RETURNS VARCHAR(100) DETERMINISTIC
BEGIN
    DECLARE sOut VARCHAR(100);
    DECLARE theLen,iLooper INT;
    SET iLooper=1;
    SET theLen=LENGTH(s);
    SET sOut='';
    WHILE iLooper<theLen DO
        IF SUBSTR(s,iLooper,1) IN ('+','-','*','/','^') THEN
            SET sOut=CONCAT(sOut,SUBSTR(s,iLooper,1));
        END IF;
        SET iLooper=iLooper+1;
    END WHILE;
    return (sOut);
END$$
DELIMITER ;

测试:

select getMOps('fish'); -- blank string
select getMOps('1+2+7-1'); -- '++-'

修改 IN 子句以满足您的喜好。我确信有更好的方法。