嘿，我来帮你搞定这个VBA的重复声明错误！咱们先拆解问题根源，再一步步修复你的代码。

为啥会出现这个错误？ #

你的代码里有几个容易踩坑的地方，刚好撞上了VBA的变量声明规则：

1. 隐式变量+显式声明的冲突：你在代码开头拼接sqlString的时候就用到了rst对象，但rst是在后面的Else块里才用Dim声明的。如果你的模块没开Option Explicit，VBA会偷偷给你创建一个隐式的rst变体变量，等你后面再显式声明rst As Recordset时，就会触发“重复声明”的报错——毕竟同一个作用域里不能有两个同名变量嘛。
2. 未声明变量的隐患：像dtTrained、sprTrained这些变量你直接拿来用，但没提前用Dim声明，VBA同样会自动创建隐式变量。要是之后你不小心在过程其他地方又声明了同名变量，冲突就来了。
3. 模块级与过程级变量重名：如果你的模块顶部已经声明了某个变量（比如qdf或者rst），然后在这个过程里又再次声明，也会报这个错。

一步步修复代码 #

1. 先开Option Explicit强制变量声明 #

这是根治隐式变量问题的关键！在你的模块最顶部加上这句：

Option Explicit

这样VBA就会强制你声明所有变量，不会偷偷给你创建隐式变量，从根源上避免很多声明冲突。

2. 把所有变量集中声明在过程开头 #

VBA里，不管你在哪个代码块（比如If、Loop）里声明变量，它的作用域都是整个过程。所以分散声明很容易不小心重复。咱们把所有要用的变量都堆在过程最开头：

Private Sub submitButton_Click() 
    Const VmfgConnStr = "Connection string is here" 
    ' 所有变量统一放这儿
    Dim qdf As QueryDef 
    Dim sqlString As String 
    Dim objAD As Object
    Dim objUser As Object
    Dim strDisplayName As String 
    Dim dtTrained As String 
    Dim sprTrained As String 
    Dim dtTrainedMsg As String 
    Dim sprTrainedMsg As String 
    Dim rst As Recordset 
    Dim recSelect As String
    Dim ConfirmMsg As String, ConfirmStyle As Integer, ConfirmTitle As String, ConfirmResponse As Integer
    
    ' 后面再写业务代码...

3. 调整sqlString的赋值位置 #

你原来的sqlString赋值在rst声明和用户输入之前，这不仅会导致rst未定义的问题，还会让所有循环都用同一个固定值（根本没用到循环里的当前记录）。咱们把sqlString的拼接放到循环内部，每次循环用当前记录的字段值：

' 循环提交记录的部分改成这样
Do Until rst.EOF 
    Debug.Print rst![EMPLOYEE_NAME]; rst![DOCUMENT_ID] 
    ' 每次循环重新拼SQL，用当前记录的字段
    sqlString = "INSERT INTO dbo.TRAINING_RECORDS (EMPLOYEE_ID, DOCUMENT_ID, REVISION, DATE_TRAINED, TRAINED_BY, STATUS, COMPETENCY, APPROVED, TYPE) " & _ 
                "SELECT '" & rst![EMPLOYEE_ID] & "', '" & rst![DOCUMENT_ID] & "', '" & rst![LATEST_REV] & "', '" & dtTrained & "', '" & sprTrained & "', 'T', 'Not Verified', 'NO', 'Internal'"
    qdf.SQL = sqlString 
    qdf.ReturnsRecords = False 
    qdf.Connect = VmfgConnStr 
    qdf.Execute 
    rst.MoveNext 
Loop 

4. 关于模块级变量的疑问 #

你提到想用模块级变量规避这个问题，确实可行，但我不太推荐——模块级变量会在整个模块的所有过程里共享值，很容易出现莫名其妙的变量污染（比如上次运行的残留值影响这次运行）。相比之下，把变量集中声明在过程开头的方式更清晰，也更容易维护。

修复后的完整代码 #

Option Explicit ' 必须放在模块最顶部！

Private Sub submitButton_Click() 
    Const VmfgConnStr = "Connection string is here" 
    Dim qdf As QueryDef 
    Dim sqlString As String 
    Dim objAD As Object
    Dim objUser As Object
    Dim strDisplayName As String 
    Dim dtTrained As String 
    Dim sprTrained As String 
    Dim dtTrainedMsg As String 
    Dim sprTrainedMsg As String 
    Dim rst As Recordset 
    Dim recSelect As String
    Dim ConfirmMsg As String, ConfirmStyle As Integer, ConfirmTitle As String, ConfirmResponse As Integer
    
    Set qdf = CurrentDb.CreateQueryDef("") 
    
    ' 获取当前AD用户的显示名
    Set objAD = CreateObject("ADSystemInfo") 
    Set objUser = GetObject("LDAP://" & objAD.UserName) 
    strDisplayName = objUser.DisplayName 
    
    ' 获取用户输入的培训日期
    dtTrained = InputBox("Enter date trained as 'mm/dd/yyyy':", "", Format(Date, "mm/dd/yyyy")) 
    Debug.Print dtTrained 
    If StrPtr(dtTrained) = 0 Then Exit Sub ' 用户取消输入
    
    ' 获取培训人
    sprTrained = InputBox("Trained By:", "", strDisplayName) 
    Debug.Print sprTrained 
    If StrPtr(sprTrained) = 0 Then Exit Sub ' 用户取消输入
    
    ' 确认是否继续操作
    ConfirmMsg = "Continue?" 
    ConfirmStyle = vbYesNo 
    ConfirmTitle = "Confirmation" 
    ConfirmResponse = MsgBox(ConfirmMsg, ConfirmStyle, ConfirmTitle) 
    If ConfirmResponse <> vbYes Then Exit Sub ' 用户选择取消
    
    ' 打开选中记录的记录集
    recSelect = "SELECT EMPLOYEE_ALL.EMPLOYEE_ID, TRAINING_DOCS_ALL.DOCUMENT_ID, TRAINING_DOCS_ALL.LATEST_REV " & _ 
                "FROM TRAINING_DOCS_ALL, EMPLOYEE_ALL " & _ 
                "WHERE EMPLOYEE_ALL.SELECTED = -1 AND TRAINING_DOCS_ALL.SELECTED = -1" 
    Set rst = CurrentDb.OpenRecordset(recSelect) 
    
    ' 循环提交每条记录
    If Not rst.EOF Then rst.MoveFirst ' 避免空记录集报错
    Do Until rst.EOF 
        Debug.Print rst![EMPLOYEE_NAME]; rst![DOCUMENT_ID] 
        ' 拼接当前记录的SQL语句
        sqlString = "INSERT INTO dbo.TRAINING_RECORDS (EMPLOYEE_ID, DOCUMENT_ID, REVISION, DATE_TRAINED, TRAINED_BY, STATUS, COMPETENCY, APPROVED, TYPE) " & _ 
                    "SELECT '" & rst![EMPLOYEE_ID] & "', '" & rst![DOCUMENT_ID] & "', '" & rst![LATEST_REV] & "', '" & dtTrained & "', '" & sprTrained & "', 'T', 'Not Verified', 'NO', 'Internal'"
        qdf.SQL = sqlString 
        qdf.ReturnsRecords = False 
        qdf.Connect = VmfgConnStr 
        qdf.Execute 
        rst.MoveNext 
    Loop 
    
    ' 后续的清理与同步操作
    CurrentDb.Execute "DELETE * FROM TRAINING_RECORDS" 
    CurrentDb.Execute "INSERT INTO TRAINING_RECORDS (EMPLOYEE_ID, DOCUMENT_ID, REVISION, DATE_TRAINED, TRAINED_BY, STATUS) " & _ 
                      "SELECT * FROM uSysTRAINING_RECORDS " & _ 
                      "WHERE EMPLOYEE_ID = '" & EMPLOYEE_ID.Value & "'" 
    CurrentDb.Execute "DELETE FROM TRAINING_NEEDED " & _ 
                      "WHERE EMPLOYEE_ID LIKE '" & EMPLOYEE_ID.Value & "' AND DOCUMENT_ID LIKE '" & DOCUMENT_ID.Value & "'" 
                      
    ' 释放对象资源，避免内存泄漏
    Set rst = Nothing
    Set qdf = Nothing
    Set objUser = Nothing
    Set objAD = Nothing
End Sub

额外提个醒 #

你现在用直接拼接SQL的方式有SQL注入风险，如果字段值里包含单引号，直接会导致SQL语法错误。建议换成参数化查询，用QueryDef的Parameters集合来传递值，这样既安全又稳定。比如：

' 示例：参数化查询的写法
qdf.SQL = "INSERT INTO dbo.TRAINING_RECORDS (EMPLOYEE_ID, DOCUMENT_ID) VALUES (@EmpID, @DocID)"
qdf.Parameters("@EmpID") = rst![EMPLOYEE_ID]
qdf.Parameters("@DocID") = rst![DOCUMENT_ID]
qdf.Execute

内容的提问来源于stack exchange，提问作者Luke