【IT168 技术文档】
我们都知道,将Data Grid的Data Source属性同Dataset相绑定,即可将数据表显示在Data Grid中,但不少初学者并不清楚:通过向Dataset中添加多个Data Table对象,每个Data Table对象装入一张表,再设定好关联,即可在Data Grid中显示多张关联表。 运行工程,会看到一个有加号按钮的视图。单击加号,窗体中出现装入的所有表名。如果查看Titles表,就会发现在每行的旁边有一个小加号按钮,点击加号,就可以查看其销售情况,如下图。
initial catalog=Pubs; data source=(local)"
'定义连接字符串
Private Sub Button1_Click(By Val sender As Object,_
By Val e As System.EventArgs) Handles Button1.Click
Dim cn As New SqlConnection (Connection String)
Cn. Open()
'建立同数据库的连接
Dim ds As New Dataset("Book Sales")
'创建Dataset对象
Dim Titles Table As New Data Table("Titles")
ds.Tables.Add(Titles Table)
'创建Data Table对象(Titles表),加入Dataset
Dim GetTitlesString As String = "Select * From Titles"
Dim da As New SqlDataAdapter(GetTitlesString, cn)
da.Fill(Titles Table)
'填充Data Table
da.Dispose()
Dim Sales Table As New Data Table("Sales")
ds.Tables.Add(Sales Table)
Dim GetSalesString As String = "Select * From Sales"
da = New SqlDataAdapter(GetSalesString, cn)
da.Fill(Sales Table)
'创建并填充Sales表
da.Dispose()
cn.Close()
Dim relation As New Data Relation("Title Sales",_
TitlesTable.Columns("title_id"),SalesTable.Columns("title_id"))
ds.Relations.Add(relation)
'根据title_id列建立两个表的关联
DataGrid1.DataSource = ds
'将DataGrid1绑定到Dataset对象(即ds)
End Sub
End Class
建立工程,添加一个Panel控件,将其Dock属性设置为Top;添加一个Splitter控件,Dock属性同样设置为Top;在窗体下部再添加一个Panel,Dock属性为top。然后,在两面板中各添加一个Data Grid,其Dock属性为Fill。窗体布局如下图。
要实现DataGrid2的内容动态更新,需要对DataGrid1的CurrentCellChanged事件进行监听,在接受到DataGrid1的变化消息后,加载相应的数据。
initial catalog=pubs; data source=(local)"
Private Sub Button1_Click(By Val sender As Object,_
By Val e As System.EventArgs) Handles Button1.Click
Dim cn As New SqlConnection(Connection String)
cn.Open()
Dim ds As New Dataset
Dim GetTitlesString As String = "Select * From Titles"
Dim Titles Table As New Data Table("Titles")
ds.Tables.Add(Titles Table)
Dim da As New SqlDataAdapter(GetTitlesString, cn)
da.Fill(Titles Table)
da.Dispose()
cn.Close()
DataGrid1.DataSource = Titles Table
’主表显示在DataGrid1中
End Sub
Private Sub DataGrid1_CurrentCellChanged(By Val sender As Object,_
By Val e As System.EventArgs) Handles DataGrid1.CurrentCellChanged
Dim titled As String = DataGrid1.Item_
(DataGrid1.CurrentCell.RowNumber, 0).To String
'判断用户在主表中选择了哪一行,取出它的第0列(在本例中即为title_id列)
Dim sql As String = "select * from sales where title_id=’" & titled & "’"
'SQL命令字符串,选择与主表中相同title_id值的从表数据
Dim cn As New SqlConnection(Connection String)
cn.Open()
Dim ds As New Dataset
Dim da As New SqlDataAdapter(sql, cn)
Dim Sales Table As New Data Table("Sales")
ds.Tables.Add(Sales Table)
da.Fill(Sales Table)
'用选择的从表数据填充,更新
da.Dispose()
cn.Close()
DataGrid2.DataSource = Sales Table
End Sub
End Class