主题：C版深夜写实例:纵向表如何变成横向表....大家来学习.

假设有表A,
经过统计后得出统计表A,
表B为固定表,
怎么才能把统计表A的数据写入表B相应的空格,而缺少的项目则自动为0??
表A

A	2
A	3
B	2
B	4
D	3

统计表A

A	5
B	6
D	3

表B

A	B	C	D	E

如果这种格式是固定的，可以直接在表B的DataColChanged事件中设置如下代码。

e.DataRow("A") = DataTables("表A").Compute("sum(第二列)","[第一列] = 'A'")+0
e.DataRow("B") = DataTables("表A").Compute("sum(第二列)","[第一列] = 'B'")+0
e.DataRow("C") = DataTables("表A").Compute("sum(第二列)","[第一列] = 'C'")+0
e.DataRow("D") = DataTables("表A").Compute("sum(第二列)","[第一列] = 'D'")+0
e.DataRow("E") = DataTables("表A").Compute("sum(第二列)","[第一列] = 'E'")+0

然后在表B的MainTableChanged事件中设置。
If Maintable.Name = "表B" Then
   DataTables("表B").DataCols("A").RaiseDataColChanged()
End If

如果一定要生成统计表，也可以这样，按钮代码：

Dim cmd As New SQLCommand
Dim 统计表A As DataTable
cmd.CommandText = "Select 第一列 , Sum(第二列) AS 第二列 From {表A} Group by 第一列"
统计表A = cmd.ExecuteReader()

Dim dt As Table = Tables("表B")
Dim dt1 As DataTable = DataTables("表A")
Dim ColNames() As String = {"A","B","C","D","E"}
For Each ColName As String In ColNames
    Dim Value As Integer
    Value = dt1.Compute("sum(第二列)","[第一列] = '" & ColName & "'")
    dt.Rows(0)(ColName) = Value
Next

要代码短也可以这样：

Dim cmd As New SQLCommand
Dim 统计表A As DataTable
cmd.CommandText = "Select 第一列 , Sum(第二列) AS 第二列 From {表A} Group by 第一列"
统计表A = cmd.ExecuteReader()
Dim ColNames() As String = {"A","B","C","D","E"}
For Each ColName As String In ColNames
    Tables("表B").Rows(0)(ColName) = DataTables("表A").Compute("sum(第二列)","[第一列] = '" & ColName & "'")+0
Next

C版必胜,申请加精!!!
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