看起来你想要把两个分别包含Credit（Debit为0）和Debit（Credit为0）的DataView合并成一行，同时包含CodeClt、Client、Credit、Debit四个字段。原代码里的Table.Merge方法会将两个表的行直接合并，最终会得到两行数据（如果两个查询都有结果），这不符合你的预期。下面提供两种可行的方案：

方案1：用SQL直接聚合（推荐） #

把合并逻辑放到数据库层，通过UNION ALL将两个查询的结果合并，再用SUM聚合得到单行数据。这种方式效率更高，代码也更简洁：

Sub Facture_old_Getdata()
    Dim sRs As String
    Dim mergedDataView As DataView
    
    ' 构造聚合查询：先合并两个表的结果，再汇总Credit和Debit
    sRs = " SELECT CodeClt, Client, SUM(Credit) As Credit, SUM(Debit) As Debit " _
          & " FROM ( " _
          & "     -- 从LV_Fact_CLient获取Credit数据，Debit设为0 " _
          & "     SELECT CodeClt, Client, Sum(MontantTTc) As Credit, 0 As Debit " _
          & "     FROM LV_Fact_CLient " _
          & "     WHERE Codeclt ='" & TxtCodeClient.Text & "'" _
          & "     GROUP BY Codeclt, Client " _
          & "     UNION ALL " _
          & "     -- 从Gestionreg获取Debit数据，Credit设为0 " _
          & "     SELECT Codeclt, Client, 0 As Credit, SUM(Montant) As Debit " _
          & "     FROM Gestionreg " _
          & "     WHERE Codeclt ='" & TxtCodeClient.Text & "'" _
          & "     GROUP BY Codeclt, Client " _
          & " ) AS Combined " _
          & " GROUP BY CodeClt, Client "
    
    ' 获取合并后的DataView，直接就是一行数据
    mergedDataView = c_DataSql.fGet_Data_ViewAccess(sRs)
    
    ' 这里可以将mergedDataView赋值给你需要的变量使用
End Sub

方案优势： #

• 数据库层面处理聚合，比客户端代码合并效率更高，尤其是数据量较大时
• 自动处理其中一个表无数据的情况（SUM会自动忽略空值，返回0）
• 代码逻辑更清晰，减少客户端的处理步骤

方案2：在VBA代码中手动合并 #

如果无法修改SQL查询，可以在代码中提取两个DataView的数值，手动创建一个包含合并后数据的DataView：

Sub Facture_old_Getdata()
    Dim sRs, sRs1 As String
    Dim dvCredit As DataView, dvDebit As DataView
    Dim resultTable As DataTable
    Dim creditValue As Double, debitValue As Double
    Dim codeClt As String, clientName As String
    
    ' 获取Credit数据视图
    sRs = " select CodeClt, client, Sum(MontantTTc) As Credit, 0 As Debit " _
          & "from LV_Fact_CLient " _
          & "where Codeclt ='" & TxtCodeClient.Text & "'" _
          & "group by Codeclt, Client"
    dvCredit = c_DataSql.fGet_Data_ViewAccess(sRs)
    
    ' 获取Debit数据视图
    sRs1 = "select Codeclt, Client, 0 As Credit, SUM(Montant) As Debit " _
           & " from Gestionreg " _
           & "where Codeclt ='" & TxtCodeClient.Text & "'" _
           & "group by Codeclt, Client"
    dvDebit = c_DataSql.fGet_Data_ViewAccess(sRs1)
    
    ' 初始化默认值
    creditValue = 0
    debitValue = 0
    codeClt = TxtCodeClient.Text
    clientName = ""
    
    ' 提取Credit值和客户名称（如果有数据）
    If dvCredit.Count > 0 Then
        creditValue = CDbl(dvCredit(0)("Credit"))
        clientName = dvCredit(0)("client").ToString()
    End If
    
    ' 提取Debit值，若之前未获取到客户名称则从这里补充
    If dvDebit.Count > 0 Then
        debitValue = CDbl(dvDebit(0)("Debit"))
        If clientName = "" Then
            clientName = dvDebit(0)("Client").ToString()
        End If
    End If
    
    ' 创建结果DataTable并定义字段
    resultTable = New DataTable()
    resultTable.Columns.Add("CodeClt", GetType(String))
    resultTable.Columns.Add("Client", GetType(String))
    resultTable.Columns.Add("Credit", GetType(Double))
    resultTable.Columns.Add("Debit", GetType(Double))
    
    ' 添加合并后的单行数据
    Dim newRow As DataRow = resultTable.NewRow()
    newRow("CodeClt") = codeClt
    newRow("Client") = clientName
    newRow("Credit") = creditValue
    newRow("Debit") = debitValue
    resultTable.Rows.Add(newRow)
    
    ' 转为DataView使用
    Dim mergedDataView As DataView = New DataView(resultTable)
End Sub

方案优势： #

• 不需要修改SQL查询逻辑，适合无法调整数据库查询的场景
• 灵活处理各种边界情况（比如其中一个查询无结果）

注意事项：SQL注入风险 #

当前代码中直接拼接TxtCodeClient.Text到SQL语句中，存在SQL注入的风险（比如用户输入包含单引号会导致SQL语法错误）。建议使用参数化查询来避免这个问题，以Access为例，可以修改为：

Sub Facture_old_Getdata()
    Dim cmd As New OleDbCommand
    Dim conn As OleDbConnection
    Dim dt As New DataTable
    Dim mergedDataView As DataView
    
    ' 获取数据库连接（替换为你实际的连接获取逻辑）
    conn = c_DataSql.GetConnection()
    
    ' 参数化SQL查询
    Dim sRs As String = " SELECT CodeClt, Client, SUM(Credit) As Credit, SUM(Debit) As Debit " _
          & " FROM ( " _
          & "     SELECT CodeClt, Client, Sum(MontantTTc) As Credit, 0 As Debit " _
          & "     FROM LV_Fact_CLient " _
          & "     WHERE Codeclt = ? " _
          & "     GROUP BY Codeclt, Client " _
          & "     UNION ALL " _
          & "     SELECT Codeclt, Client, 0 As Credit, SUM(Montant) As Debit " _
          & "     FROM Gestionreg " _
          & "     WHERE Codeclt = ? " _
          & "     GROUP BY Codeclt, Client " _
          & " ) AS Combined " _
          & " GROUP BY CodeClt, Client "
    
    cmd.CommandText = sRs
    cmd.Connection = conn
    ' 添加参数，避免SQL注入
    cmd.Parameters.AddWithValue("@CodeClt", TxtCodeClient.Text)
    cmd.Parameters.AddWithValue("@CodeClt", TxtCodeClient.Text)
    
    ' 填充DataTable
    Dim adapter As New OleDbDataAdapter(cmd)
    adapter.Fill(dt)
    
    mergedDataView = New DataView(dt)
End Sub

内容的提问来源于stack exchange，提问作者Oussama Hamadi