看见
Implementing the Equivalent of a FULL OUTER JOIN in Microsoft Access
下面是一个简短的演示:
Option Explicit
'Implementing the Equivalent of a FULL OUTER JOIN in Microsoft Jet SQL.
Private Sub Main()
'We'll do our work in App.Path, where our input files are:
ChDir App.Path
ChDrive App.Path
'Clean up from any prior test run:
On Error Resume Next
Kill "inner.txt"
Kill "left.txt"
Kill "right.txt"
Kill "c4steps.txt"
Kill "c.txt"
Kill "schema.ini"
On Error GoTo 0
With New ADODB.Connection
.Open "Provider=Microsoft.Jet.OLEDB.4.0;" _
& "Data Source='.';" _
& "Extended Properties='Text;Hdr=No'"
'Do it in 4 steps for illustration:
.Execute "SELECT [A].*, [B].[F2], [B].[F3], [B].[F4] " _
& "INTO [inner.txt] FROM " _
& "[a.txt] [A] INNER JOIN [b.txt] [B] ON " _
& "[A].[F1] = [B].[F1]", _
, _
adCmdText Or adExecuteNoRecords
.Execute "SELECT [A].*, 0 AS [B_F2], 0 AS [B_F3], 0 AS [B_F4] " _
& "INTO [left.txt] FROM " _
& "[a.txt] [A] LEFT JOIN [b.txt] [B] ON " _
& "[A].[F1] = [B].[F1] " _
& "WHERE [B].[F1] IS NULL", _
, _
adCmdText Or adExecuteNoRecords
.Execute "SELECT [B].[F1], 0 AS [A_F2], 0 AS [A_F3], 0 AS [A_F4], " _
& "[B].[F2], [B].[F3], [B].[F4] " _
& "INTO [right.txt] FROM " _
& "[a.txt] [A] RIGHT JOIN [b.txt] [B] ON " _
& "[A].[F1] = [B].[F1] " _
& "WHERE [A].[F1] IS NULL", _
, _
adCmdText Or adExecuteNoRecords
.Execute "SELECT * " _
& "INTO [c4steps.txt] FROM (" _
& "SELECT * FROM [inner.txt] UNION ALL " _
& "SELECT * FROM [left.txt] UNION ALL " _
& "SELECT * FROM [right.txt]) " _
& "ORDER BY [F1]", _
, _
adCmdText Or adExecuteNoRecords
'Do it all in one go:
.Execute "SELECT * " _
& "INTO [c.txt] FROM (" _
& "SELECT [A].*, [B].[F2], [B].[F3], [B].[F4] " _
& "FROM [a.txt] [A] INNER JOIN [b.txt] [B] ON " _
& "[A].[F1] = [B].[F1] UNION ALL " _
& "SELECT [A].*, 0 AS [B_F2], 0 AS [B_F3], 0 AS [B_F4] " _
& "FROM [a.txt] [A] LEFT JOIN [b.txt] [B] ON " _
& "[A].[F1] = [B].[F1] " _
& "WHERE [B].[F1] IS NULL UNION ALL " _
& "SELECT [B].[F1], 0 AS [A_F2], 0 AS [A_F3], 0 AS [A_F4], " _
& "[B].[F2], [B].[F3], [B].[F4] " _
& "FROM [a.txt] [A] RIGHT JOIN [b.txt] [B] ON " _
& "[A].[F1] = [B].[F1] " _
& "WHERE [A].[F1] IS NULL) " _
& "ORDER BY [F1]", _
, _
adCmdText Or adExecuteNoRecords
.Close
End With
MsgBox "Done"
End Sub
注意,我已经做了两次,一次输出
c4steps.txt
c.txt
从我的
a.txt
和
b.txt
示例输入文件。A和B是输入文件的别名,不过您可能也可以拼写出实际的文件名。
列名F1、F2、A\u F1、B\u F2等是由Jet文本IISAM生成的默认名称。再努力一点,一个正确形成的
schema.ini
浏览生成的
可能有助于了解发生了什么。
a、 txt文件
1901,1,1,1
1902,2,2,2
1904,4,4,4
1906,6,6,6
1908,8,8,8
1901,11,11,11
1902,12,12,12
1903,13,13,13
1904,14,14,14
1905,15,15,15
1906,16,16,16
1901,1,1,1,11,11,11
1902,2,2,2,12,12,12
1903,0,0,0,13,13,13
1904,4,4,4,14,14,14
1905,0,0,0,15,15,15
1906,6,6,6,16,16,16
1908,8,8,8,0,0,0