Question

我搜索过但却找不到能满足我需要的东西。我想创建一个存储函数，它将从辅助字段收集数据并返回以逗号分隔的项列表作为返回字符串。我似乎无法找到任何方法来获取我在函数中创建的变量并遍历记录集并将每个结果附加到变量，以便我可以返回它。见下文：

BEGIN
    DECLARE searchCat INT;
    DECLARE searchProd INT;
    DECLARE metas CHAR;
    SET searchCat = cat;
    SET searchProd = prod;
    SELECT * FROM offer_metas WHERE category = searchCat AND offer_id = searchProd
        gatherMeta: LOOP
                metas = metas + "," + meta_option;
                ITERATE gatherMeta;
        END LOOP gatherMeta;
    RETURN metas;
END

该函数不会保存，因为我的语法是“metas = metas + meta_option;”。我正在寻找的是将“meta_option”的当前字段值附加到当前变量“metas”的命令，这样我就可以在最后返回一个完整的列表。

有什么想法吗？

更新 - 解决方案

BEGIN
    DECLARE metas VARCHAR (300);

    SELECT GROUP_CONCAT(CONCAT(mn.title,'=',offer_metas.meta_option) ORDER BY mo.cat_seq ASC) INTO metas
    FROM offer_metas
    LEFT JOIN meta_options as mo ON mo.id = offer_metas.meta_option
    LEFT JOIN meta_names AS mn ON mn.category = mo.category AND mn.seq = mo.cat_seq 
    WHERE offer_metas.category = searchCat
    AND offer_metas.offer_id = searchProd
    ORDER BY cat_seq ASC;

    RETURN metas;
END

然后我刚刚更新了我的SQL查询，如下所示（1是我在PHP中的提议类别并填充到查询中）：

SELECT offers.*, s.short_name AS sponsorName, s.logo AS sponsorLogo, getMetas(1,offers.id) AS metas 
FROM offers 
LEFT JOIN sponsors AS s ON s.id=offers.carrier 
GROUP BY offers.id 
ORDER BY end_date ASC

Answer 1

为什么不

SELECT GROUP_CONCAT(meta_option SEPARATOR ',')
FROM offer_metas
WHERE category = searchCat AND offer_id = searchProd;

Answer 2

选项1）使用Group_Concat

选项2）use || instead of +

选项3）使用Concat（）

MySQL存储函数 - 追加字符串

2 个答案: