如何 return 更正 s 子选择的总和？

Question

我有一个子select，它是更大select的一部分。我想对一个订单的所有重量求和并显示该总和，但不断出现错误或多个返回值：

SELECT "Invoice Date", "Invoice Number", "Invoice Currency Code",    
(select sum(items.GEWICHTF) from consignment left join items on items.consid=consignment.id group by consignment.orderNo)) "Weight", 
    
FROM order
LEFT JOIN partner ON order.customer=partner.nr
LEFT JOIN consignment ON order.nr=consignment.orderno
LEFT JOIN items ON items.consid=consignment.id
LEFT JOIN transportorder ON consignment.consid=transportorder.consid

WHERE partner.nr=26601102;

我该怎么做？

Answer 1

正如你所说，你不知道什么是相关子查询，那么（阅读代码中的注释）：

SELECT "Invoice Date",
       "Invoice Number",
       "Invoice Currency Code",
       --
       -- this is a correlated subquery; it puts ITEMS table to relation with ...
       (SELECT SUM (items.gewichtf)
          FROM items 
         WHERE items.consid = consignment.id) "Weight"
  FROM t_order
       LEFT JOIN partner ON order.customer = partner.nr
       LEFT JOIN consignment ON order.nr = consignment.orderno  --> ... the CONSIGNMENT table
       LEFT JOIN items ON items.consid = consignment.id
       LEFT JOIN transportorder ON consignment.consid = transportorder.consid
 WHERE partner.nr = 26601102;

我知道，您发布的只是一小段您真正拥有的代码，所以这可能有效，也可能无效。

要对亚历克斯评论的内容发表评论：

It would be impossible to group the whole query.

不可能？另一方面，这是可能的——它只需要更多的输入，将所有 non-aggregated 列指定到 group by 子句中。

它能正常工作吗？我不知道，这取决于你想要什么。

工作的选项是创建一个函数来计算结果，然后直接从您的查询中调用该函数：

CREATE OR REPLACE FUNCTION f_weight (par_id IN items.consid%TYPE)
   RETURN NUMBER
IS
   retval  NUMBER;
BEGIN
   SELECT SUM (i.gewichtf)
     INTO retval
     FROM items i
    WHERE i.consid = par_id;

   RETURN retval;
END;
/

SELECT "Invoice Date",
       "Invoice Number",
       "Invoice Currency Code",
       --
       f_weight (consignemnt.id) "Weight"               --> here
  FROM t_order
       LEFT JOIN partner ON order.customer = partner.nr

这样做，您根本不需要 GROUP BY（除非那里有其他聚合）。

缺点？上下文切换；可能（并且将会）放慢速度。对于小数据集，您不会注意到差异。对于大型数据集，您很可能会。

最后，只是评论：这是 Oracle，我们通常讨厌将任何内容括在双引号中并在单词之间放置空格。让前端关心标签。我建议你

select invoice_date, invoice_currency_code, weight from ...

然后（如我所说）在前端使用任何你想要的标签。

Answer 2

如果所有行都在您的外部查询中（没有重复），那么您可以使用 SUM 分析函数：

SELECT "Invoice Date",
       "Invoice Number",
       "Invoice Currency Code",
       SUM(items.GEWICHTF) OVER (PARTITION BY consignment.orderNo) AS "Weight"
FROM   order
       LEFT JOIN partner ON order.customer=partner.nr
       LEFT JOIN consignment ON order.nr=consignment.orderno
       LEFT JOIN items ON items.consid=consignment.id
       LEFT JOIN transportorder ON consignment.consid=transportorder.consid
WHERE  partner.nr=26601102;

如何 return 更正 s 子选择的总和？

How to return correct sum from s subselect?

sql

oracle

select

sum

subquery