Question

我实际上有三个组合框绑定到不同的表。我的标题中出现了这样的错误。贝娄是我的代码：

myCommand = New SqlCommand("SELECT (FirstName +' '+ LastName) AS FullName FROM tblVisitor", myConnection)
   myAdapter = New SqlDataAdapter(myCommand)
   myAdapter.Fill(myDataSet, "tblVisitor")
   cboVisitor.DataSource = myDataSet.Tables(0)
   cboVisitor.DisplayMember = "FullName"
   cboVisitor.ValueMember = "VisitorID"

   'my another combobox
   myCommand = New SqlCommand("SELECT BookCode FROM tblBook", myConnection)
   myAdapter = New SqlDataAdapter(myCommand)
   myAdapter.Fill(myDataSet, "tblBook")
   cboBookCode.DataSource = myDataSet.Tables(1)
   cboBookCode.DisplayMember = "BookCode"
   cboBookCode.ValueMember = "BookCode"  'where BookCode is the pk-column of the tblBook

   'my another combobox
   myCommand = New SqlCommand("SELECT (FirstName +' '+ LastName) AS StaffFullName FROM tblStaff", myConnection)
   myAdapter = New SqlDataAdapter(myCommand)
   myAdapter.Fill(myDataSet, "tblStaff")
   cboStaff.DataSource = myDataSet.Tables(2)
   cboStaff.DisplayMember = "StaffFullName"
   cboStaff.ValueMember = "StaffID"

通过这段代码，我只得到第一个显示查询结果的comboboxt，但是其他两个没有，并显示消息'无法绑定到新值成员。参数名称：value'。请帮忙......

Answer 1

试试这个：

myCommand = New SqlCommand("SELECT (FirstName +' '+ LastName) AS FullName FROM tblVisitor;SELECT BookCode FROM tblBook;SELECT (FirstName +' '+ LastName) AS StaffFullName FROM tblStaff", myConnection)
   myAdapter = New SqlDataAdapter(myCommand)
   myAdapter.Fill(myDataSet)

   cboVisitor.DataSource = myDataSet.Tables(0)
   cboVisitor.DisplayMember = "FullName"
   cboVisitor.ValueMember = "VisitorID"

   'my another combobox
   cboBookCode.DataSource = myDataSet.Tables(1)
   cboBookCode.DisplayMember = "BookCode"
   cboBookCode.ValueMember = "BookCode"  'where BookCode is the pk-column of the tblBook

   'my another combobox
   cboStaff.DataSource = myDataSet.Tables(2)
   cboStaff.DisplayMember = "StaffFullName"
   cboStaff.ValueMember = "StaffID"

通过多次为同一数据集调用.Fill()，您感到困惑。通过只对数据库进行一次往返，这也会表现得更好。

Answer 2

VisitorID和StaffID不是Select语句的一部分。

Answer 3

您收到的错误“ ...显示消息'无法绑定到新值成员。参数名称：值'。”可能不是由于.Net代码而是SQL语句您正在使用。我有一个类似的问题，我只选择我需要的值的列。例如：

Select * from tblVisitor;

执行此操作时，您只选择FullName，ID不在数据集中。所以你需要打电话：

cboVisitor.DataSource = myDataSet.Tables(0) cboVisitor.DisplayMember = "FullName" cboVisitor.ValueMember = "VisitorID"

然后这段代码应该可以显示你的记忆：

希望这会有所帮助

vb.net - 组合框错误：'无法绑定到新值成员。参数名称：value'

3 个答案: