Question

我首先发布我的查询...

SELECT [copyright status], 
sum(IIF(layer='key info',1,0)) AS [Key Info],
sum(IIF(layer='approaches',1,0)) AS [Approaches],
sum(IIF(layer='research',1,0)) AS [Research]
FROM resources
GROUP BY [copyright status]

UNION

SELECT [lw status],
sum(IIF(layer='key info',1,0)) AS [Key Info],
sum(IIF(layer='approaches',1,0)) AS [Approaches],
sum(IIF(layer='research',1,0)) AS [Research]
FROM resources
WHERE [lw status] = 'In Reserve'
GROUP BY [lw status]

UNION 

SELECT [lw status],
sum(IIF(layer='key info',1,0)) AS [Key Info],
sum(IIF(layer='approaches',1,0)) AS [Approaches],
sum(IIF(layer='research',1,0)) AS [Research]
FROM resources
WHERE [lw status] = 'Published'
GROUP BY [lw status];

（希望这很容易阅读）

它按照我的意图工作，但是我想在查询中再添加一个函数。

在第一次SELECT查询之后，我想添加一个额外的查询，该查询总计三个总和中的每一个（关键信息，方法，研究）。我尝试添加的语法如下：

<Previous Query>
UNION
SELECT, 
sum(IIF(layer='key info',1,0)) AS [Key Info],
sum(IIF(layer='approaches',1,0)) AS [Approaches],
sum(IIF(layer='research',1,0)) AS [Research]
FROM resources
UNION 
<Next Query>

但是，当我尝试运行它时，我收到一条错误，其中显示“联合查询的两个选定查询表中的列数不匹配。”

我不确定我是否过于雄心勃勃。

此外，是否有更有效的格式化初始查询的方法？

如果它有所不同，图层，版权状态和lw状态中的值将存储在单独的表中，并通过表设计模式中的组合框绘制到资源表中。我正在使用Access 2003。

如果需要更多信息，请告知我们。

感谢。

Answer 1

union的所有部分的列数必须相等。您只需为摘要行添加null第一列：

SELECT null,
sum(IIF(layer='key info',1,0)) AS [Key Info],
sum(IIF(layer='approaches',1,0)) AS [Approaches],
sum(IIF(layer='research',1,0)) AS [Research]
FROM resources

Answer 2

您已移除lw status但未选择任何内容：

UNION
SELECT 'SUM',
sum(IIF(layer='key info',1,0)) AS [Key Info],
sum(IIF(layer='approaches',1,0)) AS [Approaches],
sum(IIF(layer='research',1,0)) AS [Research]
FROM resources
UNION 
<Next Query>

Answer 3

UNION中的每个SELECT应具有相同数量的字段（在您的情况下为4）。也许只需在SELECT中添加“stub”字段，例如空值？

UNION
 SELECT
   NULL, -- <- STUB (for padding only)
   sum(IIF(layer='key info',1,0)) AS [Key Info],
   sum(IIF(layer='approaches',1,0)) AS [Approaches],
   sum(IIF(layer='research',1,0)) AS [Research]
FROM resources
UNION

SQL - UNION查询中的Sum

3 个答案: