Question

我有两个逗号分隔ID的变量。

SET @Set1 = '1,2,3,4';
SET @Set2 = '3,2,5,6';

我想使用MySQL函数获取Set1中不在Set2中的所有元素。在上述情况下，答案是：'1,4'。

请注意，我只想使用本机MySQL函数。

Answer 1

最简单的方法是规范化您想要查找结果的集合，然后在第二集上使用FIND_IN_SET()，如此

SET @Set1 = '1,2,3,4';
SET @Set2 = '3,2,5,6';

SELECT col 
FROM
(   SELECT
        SUBSTRING_INDEX(SUBSTRING_INDEX(@Set1, ',', n.digit+1), ',', -1) col
    FROM (SELECT @set1) temp
    JOIN(SELECT 0 digit UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) n
        ON LENGTH(REPLACE(@Set1, ',' , '')) <= LENGTH(@Set1)-n.digit
    ORDER BY n.digit
) t 
WHERE NOT FIND_IN_SET(col, @set2);

如果你想捕获尽可能多的逗号分隔数字，那么就这样做

SELECT col 
FROM
(   SELECT
        SUBSTRING_INDEX(SUBSTRING_INDEX(@Set1, ',', n.digit+1), ',', -1) col
    FROM (SELECT @set1) temp
    JOIN
    (   SELECT
            SEQ.SeqValue as digit
        FROM
        (   SELECT (HUNDREDS.SeqValue + TENS.SeqValue + ONES.SeqValue) SeqValue
            FROM(SELECT 0  SeqValue UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) ONES
            CROSS JOIN(SELECT 0 SeqValue UNION ALL SELECT 10 UNION ALL SELECT 20 UNION ALL SELECT 30 UNION ALL SELECT 40 UNION ALL SELECT 50 UNION ALL SELECT 60 UNION ALL SELECT 70 UNION ALL SELECT 80 UNION ALL SELECT 90) TENS
            CROSS JOIN(SELECT 0 SeqValue UNION ALL SELECT 100 UNION ALL SELECT 200 UNION ALL SELECT 300 UNION ALL SELECT 400 UNION ALL SELECT 500 UNION ALL SELECT 600 UNION ALL SELECT 700 UNION ALL SELECT 800 UNION ALL SELECT 900) HUNDREDS
        ) SEQ
    ) n
        ON LENGTH(REPLACE(@Set1, ',' , '')) <= LENGTH(@Set1)-n.digit
    ORDER BY n.digit
) t 
WHERE NOT FIND_IN_SET(col, @set2);

将在单个逗号分隔列表中返回最多1000个项目

使用本机MySQL函数查找集合中不在另一个集合中的元素

1 个答案: