MS-访问：加入3个表

Question

有谁有如何加入3个表，我有以下语句的例子，但我得到一个缺少（语法错误“操作错误”）

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

发现问题，因为它是一个访问数据库，fisrt from语句和INNER JOIN需要在括号中，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

如果您删除WHERE子句，是否执行查询？立即跳出来的唯一的事情是你的日期不一定会成为OleDB提供者喜欢的格式。

我的猜测是，你需要封装你的日期，如'1-Jan-2009'或类似的东西。

Answer 3

您的加入看起来不错，但我认为您的问题可能是您将'TaskNumber'与'aFromDate'比较的位置;数字和日期在SQL中是不同的类型，并且会导致尝试比较它们的问题。