Question

我想在多个字段上使用相同的参数，因为我要从Access中提取一半数据，并从SQL Server中提取一半数据。 SQL Server表主要是Access表的克隆。所有新数据都进入SQL Server，但用户仍可以通过Access（通过ODBC数据源）与所有内容进行交互。

我正在尝试使用一些旧查询来与新的SQL Server表无缝地协同工作。基本上，它们看起来像这样：

SELECT [AccessCoolUsersTable].Name AS Name, [AccessCoolUsersTable].FavoriteSandwhich AS Sandwhich
FROM [AccessCoolUsersTable]
WHERE [AccessCoolUsersTable].FavoriteSandwhich = [Enter a Sandwhich]

我希望他们像这样运行（这是伪代码）

SELECT [AccessCoolUsersTable].Name As Name, [AccessCoolUsersTable].FavoriteSandwhich AS Sandwhich
FROM [AccessCoolUsersTable]
UNION
SELECT [SQLCoolUsersTable].Name As Name, [SLCoolUsersTable].FavoriteSandwhich AS Sandwhich
FROM [SQLCoolUsersTable]
WHERE 
    [AccessCoolUsersTable].FavoriteSandwhich = [Enter a Sandwhich]
    OR
    [SQLCoolUsersTable].FavoriteSandwhich = [Enter a Sandwhich]

但是发生的是，它首先提示输入“输入参数值[AccessCoolUsersTable].FavoriteSandwhich”，然后提示输入“输入参数值Enter a Sandwhich”。

我只是希望它一次询问该值，并将其用于[AccessCoolUsersTable].FavoriteSandwhich和[SQLCoolUsersTable]。有可能吗？

Answer 1

您的WHERE子句必须位于“ UNION”查询中的各个查询上。另外，您需要在查询中定义参数。

PARAMETERS [Enter a Sandwhich] Text ( 255 );
SELECT [AccessCoolUsersTable].Name As Name, [AccessCoolUsersTable].FavoriteSandwhich AS Sandwhich
FROM [AccessCoolUsersTable]
WHERE [AccessCoolUsersTable].FavoriteSandwhich = [Enter a Sandwhich]
UNION
SELECT [SQLCoolUsersTable].Name As Name, [SLCoolUsersTable].FavoriteSandwhich AS Sandwhich
FROM [SQLCoolUsersTable]
WHERE [SQLCoolUsersTable].FavoriteSandwhich = [Enter a Sandwhich]

使用联合作为子查询或

PARAMETERS [Enter a Sandwhich] Text ( 255 );
SELECT a.Name, a.FavoriteSandwhich FROM
(SELECT [AccessCoolUsersTable].Name As Name, [AccessCoolUsersTable].FavoriteSandwhich AS Sandwhich
FROM [AccessCoolUsersTable]
UNION
SELECT [SQLCoolUsersTable].Name As Name, [SLCoolUsersTable].FavoriteSandwhich AS Sandwhich
FROM [SQLCoolUsersTable]) 
AS a
WHERE a.FavoriteSandwhich = [Enter a Sandwhich]

第一个查询将具有更好的性能，因为首先使用WHERE过滤结果，然后将其添加到UNION

如何在多个字段上使用相同的参数？

1 个答案: