如何在 Excel VBA 中嵌套查询

Question

我不确定是否可能，但我正在尝试嵌套查询。 首先，我创建以下 2 个查询：

MyQuery = "Select * from " & "T1"
MyQuery2 = "Select * from " & "T2" 

然后我想比较两个查询并通过以下方式返回差异：

mkQry = "SELECT (" & MyQuery & ").*" _
                & "FROM (" & MyQuery & ") LEFT JOIN (" & MyQuery2 & ") ON " _
                & "(" & MyQuery & ".F1) = " & MyQuery2 & ".F1) AND " _
                & "(" & MyQuery & ".F2 =  " & MyQuery2 & ".F2) AND " _
                & "(" & MyQuery & ".F3 =  " & MyQuery2 & ".F3) AND " _
                & "(" & MyQuery & ".F4 =  " & MyQuery2 & ".F4) AND " _
                & "(" & MyQuery & ".F5 =  " & MyQuery2 & ".F5)" _
                & "WHERE (((" & MyQuery2 & ".F5) Is Null))"
                
        Set MyRecordset99 = MyConnection2.Execute(mkQry)
        Worksheets("TST").Range("A1").CopyFromRecordset MyRecordset99

但是， mkQry包含一个syntax error ，我不确定如何解决这个问题。

我的问题是：
是否可以按照我尝试做的方式或多或少地嵌套查询，如果可以，我如何更新语法以使其工作。

Answer 1

您应该为每个子查询取别名，然后在整个过程中使用别名。

mkQry = "SELECT x.* " _
                & "FROM (" & MyQuery & ") x LEFT JOIN (" & MyQuery2 & ") y ON " _
                & "(x.F1 = y.F1) AND " _
                ...
                & "(x.F5 = y.F5) " _
                & "WHERE (((y.F5) Is Null))"

Answer 2

您可以使用以下语法执行嵌套查询：

Select * from T1 Where Field01 In (Select Field02 from T2)

如果你想比较两个查询的结果，你可以这样做：

select T1.FieldList, T2.FieldList from T1 FULL OUTER JOIN T2 On T1.Field01 = T2.Field01

then (T1.Field01 is Null) and (T2.Field01 Not is null) ==> T2中存在但T1中不存在的所有记录

and (T1.Field01 Not is Null) and (T2.Field01 is null) ==> T1中存在但T2中不存在的所有记录

and (T1.Field01 Not is Null) and (T2.Field01 Not is null) ==> 两者都存在的所有记录

我希望它能有所帮助。