MS-Access VBA SQL, If condition in subquery, 效率提升

Question

我已经设法让我的代码工作，但是执行需要很长时间。在执行最终 SQL 语句并将该行写入 table.

之前，我使用一系列打开和关闭记录集语句来获取我正在寻找的 addr_ImportID

是否有更好的方法来使用更好的子查询、case 语句、if 条件或其他方式来完成我想要实现的目标？我对子查询的使用正在减慢速度，因此在不打开和关闭记录集的情况下操作数据可能会更有效率。或者更好的一系列 select 语句？

这是 table 的示例：

CnBio_ID | Addr_Type | Addr_ImportID | CnAdrAll_1_IDKEY | CnAdrAll_1_DateLastChanged
0001009  | Previous  | 12344         | 1                | 03/15/2014
0001009  | Home      | H2345         | 3                | 01/02/2017
0001009  | Home      | A2344         | 2                | 01/02/2017
1223144  | Previous  | 23441         | 7                | 05/23/2010
1223144  | Other     | 31333         | 6                | 08/21/2016
1223144  | Previous  | 45848         | 5                | 08/21/2016

下面的代码片段是我的代码的一部分。

strSql2 = "SELECT Addr_ImportID From [Non-Preferred Home Addresses] WHERE CnBio_ID = '" & rs(0) & "' " & _
        "AND CnAdrAll_1_DateLastChanged IN (SELECT Max(CnAdrAll_1_DateLastChanged) FROM [Non-Preferred Home Addresses] " & _
        "Where CnBio_ID = '" & rs(0) & "' AND Addr_ImportID IN (SELECT Addr_ImportID From [Non-Preferred Home Addresses] " & _
        "WHERE CnBio_ID = '" & rs(0) & "' AND Addr_Type = 'Home'));"
        Set rsMaxAddressImportID = DBEngine(0)(0).OpenRecordset(strSql2, dbOpenDynaset)
        If Not (rsMaxAddressImportID.EOF) Then
            'Condition where more than one Home address exists updated on the same date
            If (rsMaxAddressImportID.RecordCount > 1) Then
                rsMaxAddressImportID.Close
                strSql2 = "SELECT Addr_ImportID FROM [Non-Preferred Home Addresses] WHERE CnAdrAll_1_IDKEY = " & _
                "(SELECT Max(CnAdrAll_1_IDKEY) FROM [Non-Preferred Home Addresses] WHERE CnBio_ID = '" & rs(0) & "' AND Addr_Type = 'Home');"
                Set rsMaxAddressImportID = DBEngine(0)(0).OpenRecordset(strSql2, dbOpenDynaset)
                MsgBox "Row = " & i
            End If

每个 CnBio_ID
如果家庭地址存在，select Addr_ImportID 具有最大 DateLastChanged 的行
- 如果多个家庭地址在同一日期最后更新，select Addr_ImportID 行最大 CnAdrAll_1_IDKEY
如果没有家庭住址，select Addr_ImportID 具有最大 DateLastChanged 的行
- 如果多个地址在同一日期最后更新，select Addr_ImportID 行最大 CnAdrAll_1_IDKEY

在 Parfait 提问后更新

'Select Distinct CIDs to loop through
'strSql = "SELECT CnBio_ID FROM [Non-Preferred Home Addresses] WHERE CnBio_ID = '" & ConstID & "'Group By CnBio_ID;"
strSql = "SELECT CnBio_ID FROM [Non-Preferred Home Addresses] Group By CnBio_ID;"
Set rs = DBEngine(0)(0).OpenRecordset(strSql, dbOpenDynaset)

If Not (rs.EOF And rs.BOF) Then
    'MsgBox rs.RecordCount

    'This section will loop through all distinct CIDs.
    i = 1
    Do Until rs.EOF

        'Select Non-Preferred Home Address with latest date updated
        strSql2 = "SELECT Addr_ImportID From [Non-Preferred Home Addresses] WHERE CnBio_ID = '" & rs(0) & "' " & _
        "AND CnAdrAll_1_DateLastChanged IN (SELECT Max(CnAdrAll_1_DateLastChanged) FROM [Non-Preferred Home Addresses] " & _
        "Where CnBio_ID = '" & rs(0) & "' AND Addr_ImportID IN (SELECT Addr_ImportID From [Non-Preferred Home Addresses] " & _
        "WHERE CnBio_ID = '" & rs(0) & "' AND Addr_Type = 'Home'));"
        Set rsMaxAddressImportID = DBEngine(0)(0).OpenRecordset(strSql2, dbOpenDynaset)
        If Not (rsMaxAddressImportID.EOF) Then
            'Condition where more than one Home address exists updated on the same date
            If (rsMaxAddressImportID.RecordCount > 1) Then
                rsMaxAddressImportID.Close
                strSql2 = "SELECT Addr_ImportID FROM [Non-Preferred Home Addresses] WHERE CnAdrAll_1_IDKEY = " & _
                "(SELECT Max(CnAdrAll_1_IDKEY) FROM [Non-Preferred Home Addresses] WHERE CnBio_ID = '" & rs(0) & "' AND Addr_Type = 'Home');"
                Set rsMaxAddressImportID = DBEngine(0)(0).OpenRecordset(strSql2, dbOpenDynaset)
                MsgBox "Row = " & i
            End If

            'rsMaxAddressImportID.Close
        Else
            'Condition if all non-preferred addresses are not Home
            rsMaxAddressImportID.Close

            'Select max date last updated for next select statement
            maxDateSql = "SELECT Max(CnAdrAll_1_DateLastChanged) " & _
            "FROM [Non-Preferred Home Addresses] WHERE CnBio_ID = '" & rs(0) & "';"
            Set rs2 = DBEngine(0)(0).OpenRecordset(maxDateSql, dbOpenDynaset)

            strSql2 = "SELECT Addr_ImportID FROM [Non-Preferred Home Addresses] " & _
            "WHERE [Non-Preferred Home Addresses].CnBio_ID = '" & rs(0) & "' " & _
            "AND [Non-Preferred Home Addresses].CnAdrAll_1_DateLastChanged = #" & rs2(0) & "#;"
            Set rsMaxAddressImportID = DBEngine(0)(0).OpenRecordset(strSql2, dbOpenDynaset)
            'MsgBox rsMaxAddressImportID(0)
            If Not (rsMaxAddressImportID.EOF) Then
                'MsgBox rsMaxAddressImportID.RecordCount
                If (rsMaxAddressImportID.RecordCount > 1) Then
                    rsMaxAddressImportID.Close
                    strSql2 = "SELECT Addr_ImportID FROM [Non-Preferred Home Addresses] WHERE CnAdrAll_1_IDKEY = " & _
                    "(SELECT Max(CnAdrAll_1_IDKEY) FROM [Non-Preferred Home Addresses] WHERE CnBio_ID = '" & rs(0) & "' AND CnAdrAll_1_DateLastChanged = #" & rs2(0) & "#);"
                    Set rsMaxAddressImportID = DBEngine(0)(0).OpenRecordset(strSql2, dbOpenDynaset)
                    'MsgBox rsMaxAddressImportID(0)
                End If

            End If

        End If

        'Get Actual address line
        'DoCmd.RunSQL "SELECT * INTO " & _
        "[Tbl_Max_Non-Preferred_Address] " & _
        "FROM [Non-Preferred Home Addresses] WHERE [Non-Preferred Home Addresses].Addr_ImportID = '" & rsMaxAddressImportID(0) & "';"

        DoCmd.RunSQL "INSERT INTO [Tbl_Max_Non-Preferred_Address] SELECT * FROM [Non-Preferred Home Addresses] WHERE [Non-Preferred Home Addresses].Addr_ImportID = '" & rsMaxAddressImportID(0) & "';"

        rsMaxAddressImportID.Close
        rs.MoveNext
        i = i + 1

    Loop
Else
    MsgBox "There are no records in the recordset."
End If

rs.Close

"Home" 地址的意义在于，一些选民没有 "Home" 地址（参见 CnBio_ID 1223144）。
rs 是要循环的唯一 CnBio_IDs 的选择。

Thomas G 解决后更新：

总的来说，一切似乎都取得了不错的结果，但我认为存在 sorting/order 问题，我似乎无法获得正确的语法来测试。我不断收到语法错误。我对括号等的访问解释不够熟悉，无法正确处理。我正在尝试运行以下内容：

strSql_1 = "INSERT INTO [Table1] SELECT 1 AS priority, T1.CnBio_ID, T2.Max_Date, MAX(T1.Addr_IDKEY) AS MAX_IDKey " & _
        "FROM [TB - Non-Preferred Addresses] T1 " & _
        "INNER JOIN " & _
        "(" & _
            "SELECT CnBio_ID , MAX(CnAdrAll_1_DateLastChanged) AS Max_Date " & _
            "FROM [TB - Non-Preferred Addresses] " & _
            "WHERE (Addr_Type = 'Home' AND CnBio_ID = '0106228') " & _
            "GROUP BY CnBio_ID " & _
        ") T2 ON T1.CnBio_ID = T2.CnBio_ID AND T1.CnAdrAll_1_DateLastChanged = T2.Max_Date " & _
        "WHERE Addr_Type = 'Home' " & _
        "GROUP BY T1.CnBio_ID, T2.Max_Date "
strSql_2 = " UNION ALL SELECT 2 AS priority, T1.CnBio_ID, T2.Max_Date, MAX(T1.Addr_IDKEY) AS MAX_IDKey " & _
        "FROM [TB - Non-Preferred Addresses] T1 " & _
        "INNER JOIN " & _
        "(" & _
            "SELECT CnBio_ID , MAX(CnAdrAll_1_DateLastChanged) AS Max_Date " & _
            "FROM [TB - Non-Preferred Addresses] " & _
            "WHERE (Addr_Type IN ('Campus','Harris Home', 'NCOA2003','Other','Previous','Previous Home','Previous Student','Seasonal','Student') AND CnBio_ID = '0106228') " & _
            "GROUP BY CnBio_ID " & _
        ") T2 ON T1.CnBio_ID = T2.CnBio_ID AND T1.CnAdrAll_1_DateLastChanged = T2.Max_Date " & _
        "WHERE (Addr_Type IN ('Campus','Harris Home', 'NCOA2003','Other','Previous','Previous Home','Previous Student','Seasonal','Student') AND T1.CnBio_ID = '0106228') " & _
        "GROUP BY T1.CnBio_ID, T2.Max_Date " & _
        "ORDER BY CnBio_ID, priority"

Answer 1

这应该可以解决问题 SQL

SELECT V.CnBio_ID, FIRST(T.Addr_ImportID) AS Addr_ImportID , FIRST(V.Max_Date) AS CnAdrAll_1_DateLastChanged, FIRST(V.MAX_IDKey) AS CnAdrAll_1_IDKEY 
FROM [Non-Preferred Home Addresses] T
INNER JOIN
(

    SELECT 1 AS priority,  T1.CnBio_ID, T2.Max_Date, MAX(T1.CnAdrAll_1_IDKEY) AS MAX_IDKey
    FROM [Non-Preferred Home Addresses] T1
    INNER JOIN
    (
        SELECT CnBio_ID , MAX(CnAdrAll_1_DateLastChanged) AS Max_Date
        FROM [Non-Preferred Home Addresses]
        WHERE Addr_Type = 'Home'
        GROUP BY CnBio_ID
    ) T2 ON T1.CnBio_ID=T2.CnBio_ID AND T1.CnAdrAll_1_DateLastChanged=T2.Max_Date
    WHERE Addr_Type = 'Home'
    GROUP BY T1.CnBio_ID, T2.Max_Date

    UNION ALL

    SELECT 2 AS priority, T1.CnBio_ID, T2.Max_Date, MAX(T1.CnAdrAll_1_IDKEY) AS MAX_IDKey
    FROM [Non-Preferred Home Addresses] T1
    INNER JOIN
    (
        SELECT CnBio_ID , MAX(CnAdrAll_1_DateLastChanged) AS Max_Date
        FROM [Non-Preferred Home Addresses]
        WHERE Addr_Type <> 'Home'
        GROUP BY CnBio_ID
    ) T2 ON T1.CnBio_ID=T2.CnBio_ID AND T1.CnAdrAll_1_DateLastChanged=T2.Max_Date
    WHERE Addr_Type <> 'Home'
    GROUP BY T1.CnBio_ID, T2.Max_Date

    ORDER BY CnBio_ID, priority

) V 
ON T.CnBio_ID = V.CnBio_ID AND T.CnAdrAll_1_DateLastChanged=V.Max_Date AND T.CnAdrAll_1_IDKEY = V.MAX_IDKey
GROUP BY V.CnBio_ID

对于您的 table 中的每个 CnBio_ID，它将保留与您的日期逻辑相匹配的记录。您可以从中创建一个视图（查询），然后使用 CnBio_ID=anything 查询它以检索任何 CnBio_ID

的信息

不过我不知道性能是否可以接受table，主要取决于你table.

中的记录数

你应该在 :

上有索引

CnBio_ID
Addr_Type
CnAdrAll_1_IDKEY
CnAdrAll_1_DateLastChanged

如果您的类型数量有限而不是 "Home"，从性能的角度来看，明确命名它们而不是搜索“<> 'HOME'”要好得多，所以你必须改变这个：

WHERE Addr_Type <> 'Home'

到这个

WHERE Addr_Type IN ('Previous','Other')

（2 次）

如果您真的不明白发生了什么，或者需要一些解释，请告诉我。我不想无缘无故地进行冗长的解释。从分解和运行所有子查询开始，您应该会更好地理解它。

更新

要在您的代码中使用我的查询，请不要在 VBA 中硬核它！使用查询设计器从中创建查询（在标准 SQL 中，这称为视图）。 Query Designer Example in MS Access 2016

当您在设计器中时，切换到 SQL 视图。 COpy/Paste 我的查询并保存。将其命名为 Instance QRY_foo

它现在将充当 table

然后在您的 VBA 中执行此操作：

strSql2 = "SELECT * FROM QRY_Foo"
Set rsMaxAddressImportID = DBEngine(0)(0).OpenRecordset(strSql2, dbOpenDynaset)

这样您就可以更轻松地调整查询，只需从查询设计器中进行即可。

MS-Access VBA SQL, If condition in subquery, 效率提升

MS-Access VBA SQL, If condition in subquery, efficiency and improvement

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