Question

我想在计算中使用别名，但我知道这不是正确的方法。好的，我的原始代码就是这个

SELECT ROUND(SUM((`Unit_Cost`*`Quantity`)*`ExchangeRate`),2) as Cost,
 ROUND(SUM(`Unit_Cost`*`Quantity`)*`ExchangeRate`/`salesinvoice_products`.`VAT`,2) as `VATValue`
FROM `salesinvoice`
 LEFT JOIN `customers` 
   ON `salesinvoice`.`customer_id` = `customers`.`customer_id`
 LEFT JOIN `salesinvoice_products` 
  ON `salesinvoice`.`SalesInvoice_id` = `salesinvoice_products`.`SalesInvoice_id`
WHERE `PaymentTerms` > 1 
GROUP BY `salesinvoice`.`SalesInvoice_id` 
ORDER BY `DateEntered` DESC

但我想将VATValue添加到费用中。显然，如果我只做+ VATValue，它会抱怨VATValue不存在，但这就是它读取别名的方式。接下来我尝试了一个子查询，这就是答案。所以这是我的带有子查询的代码

SELECT ROUND(SUM((`Unit_Cost`*`Quantity`)*`ExchangeRate`),2) as Cost,
  (
    SELECT ROUND(SUM(`Unit_Cost`*`Quantity`)*`ExchangeRate`/`salesinvoice_products`.`VAT`,2)
    FROM `salesinvoice`
  ) as tVAT
 FROM `salesinvoice`
 LEFT JOIN `customers` 
   ON `salesinvoice`.`customer_id` = `customers`.`customer_id` 
 LEFT JOIN `salesinvoice_products` 
   ON `salesinvoice`.`SalesInvoice_id` = `salesinvoice_products`.`SalesInvoice_id`
WHERE `PaymentTerms` > 1 
GROUP BY `salesinvoice`.`SalesInvoice_id` 
ORDER BY `DateEntered` DESC

不幸的是，这次它给出了错误＃1242 - 子查询返回超过1行。我知道我先没有添加别名，但首先我只是确保子选择有效，但显然没有。

我相信我可能需要子查询中的where子句，但我不确定。

谁能告诉我我做错了什么？

Answer 1

我将执行以下操作，而不是该子查询：

SELECT `Cost`, `VATValue`, (`VATValue`+`Cost`) as CostAndVAT 
FROM
( SELECT ROUND(SUM((`Unit_Cost`*`Quantity`)*`ExchangeRate`),2) as Cost,
ROUND(SUM(`Unit_Cost`*`Quantity`)*`ExchangeRate`/`salesinvoice_products`.`VAT`,2) as `VATValue`
FROM `salesinvoice`
LEFT JOIN `customers` 
ON `salesinvoice`.`customer_id` = `customers`.`customer_id`
LEFT JOIN `salesinvoice_products` 
ON `salesinvoice`.`SalesInvoice_id` = `salesinvoice_products`.`SalesInvoice_id`
WHERE `PaymentTerms` > 1 
GROUP BY `salesinvoice`.`SalesInvoice_id` 
ORDER BY `DateEntered` DESC) a

如何在mysql的计算中使用别名，没有多行

1 个答案: