sql-access: HAVING 子句和 != 运算符答案

【问题标题】：sql-access: HAVING clause and != operatorsql-access: HAVING 子句和 != 运算符
【发布时间】：2010-05-12 02:15:30
【问题描述】：

我是访问 sql 的新手，我构建了一个如下所示的 select 语句：

SELECT [Lab Occurrence Form].[Practice Code], 
       Count([Lab Occurrence Form].[1 0 Preanalytical (Before Testing)]) AS [CountOf1 0 Preanalytical (Before Testing)], 
       [Lab Occurrence Form].[1 0 Preanalytical (Before Testing)]
  FROM [Lab Occurrence Form]
 WHERE ((([Lab Occurrence Form].[Occurrence Date]) Between #9/1/2009# And #9/30/2009#))
having ([CountOf1 0 Preanalytical (Before Testing)] != 0)
GROUP BY [Lab Occurrence Form].[Practice Code], [Lab Occurrence Form].[1 0 Preanalytical (Before Testing)];

它不喜欢我的 HAVING 子句。它有什么问题？我该怎么做！= ??

【问题讨论】：

标签： sql ms-access ms-access-2007

【解决方案1】：

它不起作用，因为HAVING 子句必须在GROUP BY 之后 - 使用：

  SELECT [Lab Occurrence Form].[Practice Code], 
         Count([Lab Occurrence Form].[1 0 Preanalytical (Before Testing)]) AS [CountOf1 0 Preanalytical (Before Testing)], 
         [Lab Occurrence Form].[1 0 Preanalytical (Before Testing)]
    FROM [Lab Occurrence Form]
   WHERE ((([Lab Occurrence Form].[Occurrence Date]) Between #9/1/2009# And #9/30/2009#))
GROUP BY [Lab Occurrence Form].[Practice Code], [Lab Occurrence Form].[1 0 Preanalytical (Before Testing)]
  HAVING Count([Lab Occurrence Form].[1 0 Preanalytical (Before Testing)]) != 0);

此外，您通常不能在 GROUP BY/HAVING 子句中使用列别名。

!= 是 ANSI 92？标准，但<> 也应该可以工作。

【讨论】：

!= 很可能是 ANSI 92 SQL，但 Access SQL92“兼容”模式不支持它——只有有效。

【解决方案2】：

使用<>。 IIRC，!= 可以在 MySQL 中工作

【讨论】：

试过了，但没有用，当我尝试运行查询时，它实际上问我 [CountOf1 0 Preanalytical (Before Testing)] 的值