主题：请老师验证下学生的代码是否正确

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按帮助文件中的“手工编码填充数据”里的代码来说的话，DataTables("表A").Select("[金额] > 100")这个代码不就是说明来源列的表吗
 

Dim Cols1() As String = {"来源列一","来源列二","来源列三"}
Dim Cols2() As String = {"接收列一","接收列二","接收列三"}
For Each dr1 As DataRow In DataTables("表A").Select("[金额] > 100")
    Dim dr2 As DataRow = DataTables("表B").AddNew()
    For i As Integer = 0 To Cols1.Length -1
        dr2(Cols2(i)) = dr1(Cols1(i))
    Next
Next

 

再回过头来看外部的，dt.DataRows 数据来源与外部数据里的（员工）表，既然数据来源与外部表， Dim nr As DataRow = DataTables("员工").AddNew()，这个又代表什么？自相矛盾？实在不解错误的原因在哪

 

Dim sCols() As String = {"列名1", "列名2", "列名3"}
Dim dCols() As String = {"列名A", "列名B", "列名C"}
cmd.ConnectionName = "数据源名称"
cmd.CommandText = "SELECT * From {员工}"
dt = cmd.ExecuteReader()    

For Each dr As DataRow In dt.DataRows
    Dim nr As DataRow = DataTables("员工").AddNew()
    For i As Integer =0 To sCols.Length -1
        nr(dCols(i)) = dr(sCols(i))
    Next
Next     

再回过头重新看了下帮助文件里

 

例如项目中有一个员工表，要从一个外部文件中合并数据到这个员工表中，希望在合并过程中检查身份证号码，如果员工表已经存在相同身份证号码的行，则跳过此行。
假定被合并的表和员工表的结构相同，代码如下：

 

 

Dim cmd As New SQLCommand
Dim dt As DataTable
cmd.ConnectionName = "数据源名称"
cmd.CommandText = "SELECT * From {员工}"
dt = cmd.ExecuteReader()
For Each dr As DataRow In dt.DataRows
    If DataTables("员工").Find("身份证号码 = '" & dr("身份证号码") & "'") Is Nothing Then
        Dim nr As DataRow = DataTables("员工").AddNew()
        For Each dc As DataCol In dt.DataCols
            nr(dc.name) = dr(dc.name)
        Next
    End If
Next

 

可见要自己设计一个功能更强的Merger，其实是件很简单的事情。

如果两个表的结构不同，可以参考下面的代码：

Dim cmd As New SQLCommand
Dim dt As DataTable
Dim sCols() As String = {"列名1", "列名2", "列名3"}
Dim dCols() As String = {"列名A", "列名B", "列名C"}
cmd.ConnectionName = "数据源名称"
cmd.CommandText = "SELECT * From {员工}"
dt = cmd.ExecuteReader()
For Each dr As DataRow In dt.DataRows
    Dim nr As DataRow = DataTables("员工").AddNew()
    For i As Integer =0 To sCols.Length -1
        nr(dCols(i)) = dr(sCols(i))
    Next
Next

 

“要从一个外部文件中合并数据到这个员工表中”这个说明是不是错误了，既然要从外部文件中合并数据到员工表，为什么还要从外部的员工表中读取数据？这样的话打个比方外部文件用“表A”来说明

cmd.CommandText = "SELECT * From {员工}"  这个代码不是要改成   cmd.CommandText = "SELECT * From {表A}"   ？？？？数据来源是“表A”不是员工表。

 

再从帮助文件里的“手工编码填充数据”里的代码来看

 

Dim Cols1() As String = {"来源列一","来源列二","来源列三"}
Dim Cols2() As String = {"接收列一","接收列二","接收列三"}
For Each dr1 As DataRow In DataTables("表A").Select("[金额] > 100")
    Dim dr2 As DataRow = DataTables("表B").AddNew()
    For i As Integer = 0 To Cols1.Length -1
        dr2(Cols2(i)) = dr1(Cols1(i))
    Next
Next

 

指定来源数据为表A，接收的为表B，代码执行完全没错误，一切正常

 

天那~~~~到底是我错了，还是帮助文件错了？

Dim cmd As New SQLCommand
Dim dt As DataTable
Dim sCols() As String = {"日期", "销售金额", "付款渠道"}
Dim dCols() As String = {"日期", "收入", "收入渠道"}
cmd.C
cmd.CommandText = "SELECT * From {销售订单}"
dt = cmd.ExecuteReader()
For Each dr As DataRow In dt.DataRows
    Dim fdr As DataRow = DataTables("账面明细").Find("日期 = '" & dr("日期") & "'")
    If fdr IsNot Nothing Then
        If fdr("项目") = "门市收入"
            fdr("收入") = DataTables("销售订单").Compute("Sum(销售金额)", "日期 = '" & dr("日期") & "'")
        Else
            Dim nr As DataRow = DataTables("账面明细").AddNew()
            For i As Integer =0 To sCols.Length -1
                nr(dCols(i)) = dr(sCols(i))
            Next
            nr("项目") = "门市收入"
        End If
    End If
Next

 

最后代码改为这样，无效！

 

Dim cmd As New SQLCommand
Dim dt As DataTable
cmd.C
cmd.CommandText = "SELECT * From {销售订单}"
dt = cmd.ExecuteReader()
For Each dr As DataRow In dt.DataRows
    If DataTables("销售订单").Find("日期 = '" & dr("日期") & "'") Is Nothing Then     
        Dim nr As DataRow = DataTables("账面明细").AddNew()
        For Each dc As DataCol In dt.DataCols
            nr(dc.name) = dr(dc.name)
        Next
    End If  
Next

 

按照自己表里的列名进行更改后测试无效！两张表列类型都一样

 

 

Dim cmd As New SQLCommand
Dim dt As DataTable
cmd.ConnectionName = "数据源名称"
cmd.CommandText = "SELECT * From {员工}"
dt = cmd.ExecuteReader()
For Each dr As DataRow In dt.DataRows
    If DataTables("员工").Find("身份证号码 = '" & dr("身份证号码") & "'") Is Nothing Then
        Dim nr As DataRow = DataTables("员工").AddNew()
        For Each dc As DataCol In dt.DataCols
            nr(dc.name) = dr(dc.name)
        Next
    End If
Next

 

 

再测试底下那代码，测试成功，员工表增加了一行，并把指定的数据填充

Dim cmd As New SQLCommand
Dim dt As DataTable
Dim sCols() As String = {"来源列一", "来源列二", "来源列三"}
Dim dCols() As String = {"接收列一", "接收列二", "接收列三"}
cmd.C
cmd.CommandText = "SELECT * From {表G}"
dt = cmd.ExecuteReader()
For Each dr As DataRow In dt.DataRows
    Dim nr As DataRow = DataTables("员工").AddNew()
    For i As Integer =0 To sCols.Length -1
        nr(dCols(i)) = dr(sCols(i))
    Next
Next

 呵呵，楼主自己捣鼓出来了。学习就应该是这样的，拿来即用的没有什么成就感。

林总又取笑我了，我想实现条件填充那又得怎么实现，代码不起作用啊

老爹人呢，代码到底怎么的搞法