Mysql 如何在SQL select语句中选择组合类别名称？

我有一个选择声明如下：

SELECT 
  sales.Added_by as "Added_By",
  CONCAT(HOUR(sales.Sales_Date), ':00-', HOUR(sales.Sales_Date)+2, ':00') AS Hours,
  COUNT(sales.Sales_ID) AS `Sales_ID`,
  sum(sales.Quantity) as "Quantity",
  sum(sales.Tax_Amount) as "Tax_Amount",
  sum(sales.Discount_Amount) as "Discount_Amount",
  sum(sales.Total_Price) as "Total_Price",
  sum(sales.Cash) as "Cash",
  sum(sales.Change) as "Change",
  MAX(sales_detail.Category_ID) as "Category_ID",
  MAX(sales_detail.Stock_Name) as "Stock_Name",
  categories.Category_Name
FROM sales
  inner join sales_detail on sales.Sales_Number=sales_detail.Sales_Number
  inner join categories on categories.Category_ID = sales_detail.Category_ID
GROUP BY HOUR(sales.Sales_Date) asc, sales.Added_By asc 

我的问题是如何在中添加类别的名称

MAX(sales_detail.Category_ID) as "Category_ID"

专栏？输出应类似于

1-类别A

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非常感谢您的帮助。

mysql特定用途的一种黑客方法

GROUP\u CONCAT

获取按类别id降序排列的每个组的以逗号分隔的类别列表，然后使用

SUBSTRING\u INDEX

字符串函数选择第一个值

SUBSTRING_INDEX(
     GROUP_CONCAT(categories.name ORDER BY categories.Category_ID DESC)
,',',1) "Category_Name",

但我如何才能将其添加到category\u id列中呢

---

mysql特有的一种黑客方法是使用

GROUP\u CONCAT

为每个组获取以逗号分隔的类别列表，按类别id降序排列，然后使用

SUBSTRING\u INDEX

string函数选择第一个值

SUBSTRING_INDEX(
     GROUP_CONCAT(categories.name ORDER BY categories.Category_ID DESC)
,',',1) "Category_Name",

但我如何才能将其添加到category\u id列中呢

---

如果分组在一起的所有行的类别名称始终相同，则只需将

categories.category\u name

添加到

GROUP BY

子句中，并像往常一样对列名进行压缩：

SELECT 
  sales.Added_by as "Added_By",
  CONCAT(HOUR(sales.Sales_Date), ':00-', HOUR(sales.Sales_Date)+2, ':00') AS Hours,
  COUNT(sales.Sales_ID) AS `Sales_ID`,
  sum(sales.Quantity) as "Quantity",
  sum(sales.Tax_Amount) as "Tax_Amount",
  sum(sales.Discount_Amount) as "Discount_Amount",
  sum(sales.Total_Price) as "Total_Price",
  sum(sales.Cash) as "Cash",
  sum(sales.Change) as "Change",
  MAX(sales_detail.Category_ID) || ' - ' || categories.Category_Name as "Category_ID",
  MAX(sales_detail.Stock_Name) as "Stock_Name",
  categories.Category_Name
FROM sales
  inner join sales_detail on sales.Sales_Number=sales_detail.Sales_Number
  inner join categories on categories.Category_ID = sales_detail.Category_ID
GROUP BY HOUR(sales.Sales_Date) asc, sales.Added_By asc, categories.Category_Name 

---

如果分组在一起的所有行的类别名称始终相同，则只需将

categories.category\u name

添加到

GROUP BY

子句中，并像往常一样对列名进行压缩：

SELECT 
  sales.Added_by as "Added_By",
  CONCAT(HOUR(sales.Sales_Date), ':00-', HOUR(sales.Sales_Date)+2, ':00') AS Hours,
  COUNT(sales.Sales_ID) AS `Sales_ID`,
  sum(sales.Quantity) as "Quantity",
  sum(sales.Tax_Amount) as "Tax_Amount",
  sum(sales.Discount_Amount) as "Discount_Amount",
  sum(sales.Total_Price) as "Total_Price",
  sum(sales.Cash) as "Cash",
  sum(sales.Change) as "Change",
  MAX(sales_detail.Category_ID) || ' - ' || categories.Category_Name as "Category_ID",
  MAX(sales_detail.Stock_Name) as "Stock_Name",
  categories.Category_Name
FROM sales
  inner join sales_detail on sales.Sales_Number=sales_detail.Sales_Number
  inner join categories on categories.Category_ID = sales_detail.Category_ID
GROUP BY HOUR(sales.Sales_Date) asc, sales.Added_By asc, categories.Category_Name 

---

嗨，麦克穆尼，类别将不同。嗨，麦克穆尼，类别将不同。嗨，哈立德，这个选择语句是正确的。但我如何才能同时添加到category _id列中？@Test87您是指id categoryname？像这样的12种食物？@Khalid，非常感谢你的回答，这正是我想要的。令人惊叹的！嗨，Khalid，这个select语句是正确的。但我如何才能同时添加到category _id列中？@Test87您是指id categoryname？像这样的12种食物？@Khalid，非常感谢你的回答，这正是我想要的。令人惊叹的！