mysql中find_in_set()函数用法及自定义增强函数

select FIND_IN_SET('1', '1,2,3');
// 结果：1
select FIND_IN_SET('3', '1,2,3');
// 结果：3
select FIND_IN_SET('4', '1,2,3');
// 结果：0
// 后一个包含前一个返回大于0的元素所在位置,不包含前一个则返回0

CREATE FUNCTION `FIND_PART_IN_SET`(str1 text, str2 text)
    RETURNS text
BEGIN
    #传入两个逗号分割的字符串，判断第二个字符串是否包含第一个字符串split之后的单个
    DECLARE CURRENTINDEX INT;#当前下标
    DECLARE CURRENTSTR text;
    DECLARE result int;
    set result = 0;
    set CURRENTINDEX = 0;
    set CURRENTSTR = '';
    IF str1 IS NOT NULL AND str1 != '' THEN
        SET CURRENTINDEX = LOCATE(',', str1);
        WHILE CURRENTINDEX > 0
            DO
                SET CURRENTSTR = substring(str1, 1, CURRENTINDEX - 1);
                if FIND_IN_SET(CURRENTSTR, str2)>0 THEN
                    set result = 1;
                end if;
                SET str1 = substring(str1, CURRENTINDEX + 1);
                SET CURRENTINDEX = LOCATE(',', str1);
            END WHILE;
        #只传一个 和 最后无逗号的情况
        IF LENGTH(str1) > 0 THEN
            if FIND_IN_SET(str1, str2)>0 THEN
                set result = 1;
            end if;
        END IF;
    END IF;
    RETURN result;
END;

CREATE FUNCTION `FIND_ALL_PART_IN_SET`(str1 text, str2 text)
    RETURNS text
BEGIN
    #传入两个逗号分割的字符串，判断第二个字符串是否全部包含第一个字符串split之后的单个
    DECLARE CURRENTINDEX INT;#当前下标
    DECLARE CURRENTSTR text;
    DECLARE RESULT int;
    DECLARE TOTALCOUNT int;
    DECLARE TRUECOUNT int;
    set RESULT = 0;
    set CURRENTINDEX = 0;
    set CURRENTSTR = '';
    set TOTALCOUNT = 0;
    set TRUECOUNT = 0;
    IF str1 IS NOT NULL AND str1 != '' THEN
        SET CURRENTINDEX = LOCATE(',', str1);
        WHILE CURRENTINDEX > 0
            DO
                SET TOTALCOUNT = TOTALCOUNT + 1;
                SET CURRENTSTR = substring(str1, 1, CURRENTINDEX - 1);
                if FIND_IN_SET(CURRENTSTR, str2)>0 THEN
                    SET TRUECOUNT = TRUECOUNT + 1;
                end if;
                SET str1 = substring(str1, CURRENTINDEX + 1);
                SET CURRENTINDEX = LOCATE(',', str1);
            END WHILE;
        #只传一个 和 最后无逗号的情况
        IF LENGTH(str1) > 0 THEN
            SET TOTALCOUNT = TOTALCOUNT + 1;
            if FIND_IN_SET(str1, str2)>0 THEN
                SET TRUECOUNT = TRUECOUNT + 1;
            end if;
        END IF;
    END IF;
    IF TOTALCOUNT > 0 AND TRUECOUNT = TOTALCOUNT THEN
        SET RESULT = 1;
    END IF;
    RETURN result;
END;