Question

这应该很简单，但我收到“无效的列名称”错误。

SELECT Transaction, COUNT(ItemId) AS ItemCount
FROM TransactionTable
WHERE ItemCount > 5
GROUP BY Transaction
ORDER BY ItemCount DESC

这个语句在没有WHERE子句的情况下工作，因为ORDER BY正在使用列别名，所以这对我来说似乎是双重标准。

Answer 1

使用HAVING并再次指定计数

SELECT Transaction, COUNT(ItemId) AS ItemCount
FROM TransactionTable
GROUP BY Transaction
HAVING COUNT(ItemId) > 5
ORDER BY ItemCount DESC

ORDER BY使用别名的原因是因为SQL查询按此顺序处理

FROM（incl join）
ON
OUTER
WHERE
GROUP BY HAVING
SELECT
订购单 TOP

Answer 2

SELECT [Transaction], COUNT(ItemId) AS ItemCount
FROM TransactionTable
WHERE ItemCount > 5
GROUP BY COUNT(ItemId) 
ORDER BY COUNT(ItemId) DESC

Answer 3

您可以在ORDER BY中引用列别名（逻辑上）在SELECT之后处理。要在WHERE或HAVING子句中使用列别名，您可以在表格表达式中定义SELECT，例如如下。

;WITH cte
     AS (SELECT Transaction ,
                COUNT(itemid) AS itemcount
         FROM   transactiontable
         GROUP  BY Transaction )
SELECT Transaction ,
       itemcount
FROM   transactiontable
WHERE  itemcount > 5
ORDER  BY itemcount DESC

Answer 4

WITH tempTable AS
(
  SELECT Transaction, COUNT(ItemId) AS ItemCount
  FROM TransactionTable
)
SELECT * 
FROM tempTable
WHERE ItemCount > 5
GROUP BY Transaction
ORDER BY ItemCount DESC

SQL查询在ALIAS列上使用WHERE

4 个答案: