mysql#1242-子查询返回超过1行

这是我的论文，死胡同是后来我不知道我做错了什么。。我希望有人能帮我知道这里出了什么问题谢谢

SELECT 
        flower_id,
        flower_name,
        flower_description,
        flower_price,
        flower_category,
        (quantity - (SELECT 
                SUM(q.quantity_value)
            FROM
                orders_details od
                    INNER JOIN
                cart_details cd ON cd.cart_id = od.cart_id
                    INNER JOIN
                quantities q ON q.quantity_id = cd.quantity_id
            WHERE
                od.flag = 1 AND cd.flower_id = flower_id
            GROUP BY cd.flower_id)) AS 'quantity',
        mfg_date,
        exp_date
    FROM
        flower_details,
        categories
    WHERE
        flower_details.flower_category = categories.category_id

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我在这里做的是从客户购买的产品的总数量减去存货

如果子选择返回的行数超过a，则应使用子选择上的内部联接来联接总和 如果subselect返回的行数超过a，则应使用subselect上的内部联接subselect上的内部联接来联接总和

      SELECT 
        flower_details.flower_id,
        flower_name,
        flower_description,
        flower_price,
        flower_category,
        flower_details.quantity - t1.quantity, 
        mfg_date,
        exp_date
    FROM flower_details 
    INNER JOIN categories ON flower_details.flower_category = categories.category_id
    INNER JOIN       (
                SELECT  cd.flower_id , 
                SUM(q.quantity_value) AS quantity
            FROM
                orders_details od
                    INNER JOIN
                cart_details cd ON cd.cart_id = od.cart_id
                    INNER JOIN
                quantities q ON q.quantity_id = cd.quantity_id
            WHERE
                od.flag = 1 AND cd.flower_id = flower_id
            GROUP BY cd.flower_id
    )  t1 on flower_details.flower_id = t1.flower_id

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你想要什么？你得到了什么？从产品库存中得到产品的差异总数-客户购买的产品和产品的一些信息尝试只执行子查询并调试iti，它已经这样做了，它说#1242-子查询返回超过1行请帮助我。我不知道这里出了什么问题字段列表中的“数量”列不明确字段列表中的“数量”列不明确先生：（减法运算在哪里）添加了减法，删除了数量模糊性..答案已更新。我将od.flower\u id改为flower\u id先生