Ms-Access：联接3个表

Question

有没有人有一个如何联接3个表的示例，我有以下语句，但是却丢失了（语法错误“运算符错误”）

da = New OleDbDataAdapter("SELECT [S].[Scheduled Vege], [V].[Description], 
        [DS].[Task], [DS].[Task Date], [DS].[Completed] FROM [Scheduled] AS S 
        INNER JOIN [Date Schedules] AS DS ON [S].[SchedID] = [DS].[SchedID] 
        INNER JOIN [Vegetables Descriptions] AS V ON [V].[Task] = [DS].[Task] 
        WHERE [DS].[TaskNumber] >= " & aFromDate & " AND [DS].[TaskNumber] <= " & aToDate & " 
        AND [DS].[Completed] = '" & aCompleted & "' ", conn)

谢谢

Answer 1

发现了问题，因为它是一个访问数据库，所以fisrt from语句和INNER JOIN需要放在方括号中，如下所示。

da = New OleDbDataAdapter("SELECT [S].[Scheduled Vege], [V].[Description], 
[DS].[Task], [DS].[Task Date], [DS].[Completed] FROM ([Scheduled] AS S 
INNER JOIN [Date Schedules] AS DS ON [S].[SchedID] = [DS].[SchedID]) 
INNER JOIN [Vegetables Descriptions] AS V ON [V].[Task] = [DS].[Task] 
WHERE [DS].[TaskNumber] >= " & aFromDate & " AND [DS].[TaskNumber] <= " & aToDate & " 
AND [DS].[Completed] = '" & aCompleted & "' ", conn)

Answer 2

如果删除WHERE子句，是否执行查询？ 唯一让我惊讶的是您的约会不一定是OleDB提供程序想要的格式。

我的猜测是您需要封装日期，例如“ 2009年1月1日”或类似内容。

Answer 3

您的加入看起来还不错，但是我认为您的问题可能是您正在将“ TaskNumber ”与“ aFromDate ”进行比较； 数字和日期在SQL中是不同的类型，并且在尝试像这样比较它们时应引起问题。