从 3 个具有动态值的表中透视

Question

我想使用下表创建一个数据透视表，但在此之前这是我的表

tbl_branch

tbl_product

tbl_orders

现在。它们都是动态的，意味着很快我将添加新的分支，新的项目，订单将继续。现在这是我想要实现的输出。

如何添加每个分支和项目的总数量？基本上它是一个数据透视表。如果是静态的就好了，但是3张表会不断的添加数据。

Answer 1

一个示例数据透视表查询如下所示：

select p.description as item,
  sum(case o.branch_id when 1 then o.qty else 0 end) as `Branch 1`,
  sum(case o.branch_id when 2 then o.qty else 0 end) as `Branch 2`,
  sum(case o.branch_id when 3 then o.qty else 0 end) as `Branch 3`,
  sum(case o.branch_id when 4 then o.qty else 0 end) as `Branch 4`,
  sum(case o.branch_id when 5 then o.qty else 0 end) as `Branch 5`,
  sum(case o.branch_id when 6 then o.qty else 0 end) as `Branch 6`,
  sum(o.qty) as `Total Qty`
from tbl_product as p
join tbl_orders as o on p.id = o.item_id
join tbl_branch as b on o.branch_id = b.id
group by p.id;

输出：

+-----------+----------+----------+----------+----------+----------+----------+-----------+
| item      | Branch 1 | Branch 2 | Branch 3 | Branch 4 | Branch 5 | Branch 6 | Total Qty |
+-----------+----------+----------+----------+----------+----------+----------+-----------+
| Product 1 |       12 |        0 |       67 |        1 |        0 |        0 |        80 |
| Product 2 |        3 |        0 |        0 |        0 |        1 |        0 |         4 |
| Product 3 |        1 |        4 |        0 |        0 |        0 |        0 |         5 |
| Product 4 |        2 |        0 |        5 |        0 |        0 |        0 |         7 |
| Product 5 |        0 |        0 |        0 |        0 |        0 |        3 |         3 |
+-----------+----------+----------+----------+----------+----------+----------+-----------+

您问如何使这种“动态化”，因为您会定期获得新产品和新分支。

SQL 要求选择列表的所有列在解析查询时都是固定的。在检查数据时，您不能根据在执行期间发现的不同值的数量来动态扩展其列列表的任何 SQL 查询。

尝试根据查询结果扩展其选择列表的查询就像编写一个 PHP 函数，其参数数量取决于函数的返回值！换句话说，这是一个先有鸡还是先有蛋的问题。您必须在调用之前定义函数，并且函数的定义取决于该函数返回的结果。这毫无意义。

因此，所有数据透视表样式的查询都必须在两个单独的 SQL 查询中完成：

1. 获取要转换为列的不同值的列表。例如：

    select id, branch_name from tbl_branch;
   

2. 将第一个查询的结果格式化为数据透视表查询的选择列表，就像我之前展示的那样。

如果您不想运行两个 SQL 查询，另一种方法是不在 SQL 中进行数据透视。只需获取数据库中存在的行，然后编写代码以将结果“透视”为您喜欢的表格演示文稿。

Answer 2

您可以进行动态查询，因为您永远不知道将来会拥有哪些分支和产品

架构 (MySQL v8.0)

CREATE TABLE tbl_branch (
  `ID` INTEGER,
  `Branch_Name` VARCHAR(8)
);

INSERT INTO tbl_branch
  (`ID`, `Branch_Name`)
VALUES
  ('1', 'Branch 1'),
  ('2', 'Branch 2'),
  ('3', 'Branch3'),
  ('4', 'Branch4'),
  ('5', 'Branch5'),
  ('6', 'Branch 6');
  

CREATE TABLE tbl_product (
  `ID` INTEGER,
  `Description` VARCHAR(10)
);

INSERT INTO tbl_product
  (`ID`, `Description`)
VALUES
  ('1', 'Product 1'),
  ('2', 'Product2'),
  ('3', 'Product 3'),
  ('4', 'Product 4'),
  ('5', 'Product 5'),
  ('6', 'Product 6'),
  ('7', 'Product 7'),
  ('8', 'Product 8'),
  ('9', 'Product 9'),
  ('10', 'Product 10');

CREATE TABLE tbl_orders (
  `ID` INTEGER,
  `Branch_ID` INTEGER,
  `Item_ID` INTEGER,
  `Qty` INTEGER
);

INSERT INTO tbl_orders
  (`ID`, `Branch_ID`, `Item_ID`, `Qty`)
VALUES
  ('1', '1', '1', '12'),
  ('2', '1', '2', '3'),
  ('3', '2', '3', '4'),
  ('4', '3', '4', '5'),
  ('5', '3', '1', '67'),
  ('6', '4', '1', '1'),
  ('7', '5', '2', '1'),
  ('8', '1', '3', '1'),
  ('9', '1', '4', '2'),
  ('10', '6', '5', '3');

---

查询 #1

SELECT 
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'SUM(CASE o.`Branch_ID` WHEN "',
     o.`Branch_ID`,
      '" THEN o.`Qty` ELSE 0 END) AS `',
      b.`Branch_Name`, '`'      
    )
    ORDER BY o.`Branch_ID`
  ) 
  INTO @sql
FROM tbl_product as p
JOIN tbl_orders as o on p.ID = o.Item_ID
JOIN tbl_branch as b on o.Branch_ID = b.ID;
SET @sql = CONCAT('SELECT p.Description as item,',@sql,
                  ', SUM(o.Qty) as `Total Qty` FROM tbl_product as p
JOIN tbl_orders as o on p.ID = o.Item_ID
JOIN tbl_branch as b on o.Branch_ID = b.ID GROUP BY p.id,p.Description;');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

| item      | Branch 1 | Branch 2 | Branch3 | Branch4 | Branch5 | Branch 6 | Total Qty |
| --------- | -------- | -------- | ------- | ------- | ------- | -------- | --------- |
| Product 1 | 12       | 0        | 67      | 1       | 0       | 0        | 80        |
| Product2  | 3        | 0        | 0       | 0       | 1       | 0        | 4         |
| Product 3 | 1        | 4        | 0       | 0       | 0       | 0        | 5         |
| Product 4 | 2        | 0        | 5       | 0       | 0       | 0        | 7         |
| Product 5 | 0        | 0        | 0       | 0       | 0       | 3        | 3         |

---

View on DB Fiddle