[英]“No data exists for the row/column” when connecting to SQL database from VB.net
我正在尝试创建一个具有datagridview的程序,当用户单击视图中的单元格时,它会查找SQL数据库,从同一记录中的其他字段中获取信息,并自动填充相应的文本框(完成通过操作表单中的字段名称)。
但是出于某种原因,我收到一条错误消息:“InvalidOperationException未处理”“行/列没有数据”
以下是与该程序的这一部分相关的代码:
Private Sub DataGridView1_CellMouseClick(sender As Object, e As DataGridViewCellMouseEventArgs) Handles dgvResults.CellMouseClick
' Set values in the text boxes to both corresponding to the film.
Dim strFields() As String = {"ID", "fName", "fGenre", "fSynopsis", "fAgeRating", "fActorsActresses", "fWebRating", "fNoReservations", "fWeeksRunning"}
Dim Con = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=ApplicationData.accdb;Persist Security Info=False;")
Con.Open() 'Open the connection
Dim Cmd As New OleDbCommand(StringBuilderCommand("*", "Films", dgvResults.CurrentCell.Value, "fName"), Con) 'Create a string by calling the StringBuilderCommand to combine the parameters together with quotes.
Cmd.CommandType = CommandType.Text
Dim Rdr As OleDbDataReader = Cmd.ExecuteReader()
Dim intCount As Integer = 4 ' Create a loop variable.
Do While Rdr.Read() Or intCount < 6 ' While this statement is 'TRUE', e.g. there is a valid record.
strResult = "txt" & strFields(intCount).Replace("f", "") 'Remove any instances of 'f', e.g. the prefix of the string.
txtActorsActresses.Text = StringBuilderCommand("*", "Films", dgvResults.CurrentCell.Value, "fName")
Me.Controls(strResult).Text = Rdr.Item(strFields(intCount)) ' Suspect the error lies here.
'Set the text-box to the correct value from the database.
'This will allow me to go through several text boxes, and grab their corresponding values from the database.
intCount = intCount + 1
'Current error is because it cannot find any data beyond the first field taken.
'I have no idea why this is. But if I change the starting intCount value, it will successfully take a different value.
Loop
Rdr.Close() 'Cleaning up.
Cmd.Dispose()
Con.Close()
WebBrowser1.Navigate(dgvResults.CurrentCell.Value.Replace(" ", ".") & ".movie.poster.new.jpg.to") 'Grab the movie poster off the internet corresponding to the films name.
End Sub
Private Function StringBuilderCommand(Field, Table, CurrentCellValue, SearchParameter)
'Creates a suitable SQL string.
Dim MyStringBuilder As New StringBuilder("SELECT ")
MyStringBuilder.Append("*") ' Append the parameter 'Field'.
MyStringBuilder.Append(" FROM ") ' Append the SQL command 'FROM'.
MyStringBuilder.Append(Table) ' Append the parameter 'Table'.
MyStringBuilder.Append(" WHERE ") ' Append the SQL command 'WHERE'.
MyStringBuilder.Append(SearchParameter) ' Append the parameter 'SearchParameter'.
MyStringBuilder.Append("=""")
MyStringBuilder.Append(CurrentCellValue) ' Append the parameter 'CurrentCellValue', representing the cell selected.
MyStringBuilder.Append("""") 'Append a quotation mark.
Return MyStringBuilder.ToString() ' Return it to the main program.
End Function
数据库表连接到:
在Visual Studio 2012 Express中查看错误的视图:
'dgvResults.CurrentCell.Value'的值是从数据库中取出的电影的名称(例如“12年奴隶”)。
我究竟做错了什么?
谢谢,
C。
问题是由传递给读者的strFields(intCount)的值引起的。 它不是有效的列索引。
您可能希望在再次在DataReader()
上循环之前循环字段,如:
Do While Rdr.Read()
For intCount as Integer = 4 to 6
strResult = "txt" & strFields(intCount).Replace("f", "")
txtActorsActresses.Text = StringBuilderCommand("*", "Films", dgvResults.CurrentCell.Value, "fName")
Me.Controls(strResult).Text = Rdr.Item(strFields(intCount))
Next
Loop
我删除了Dim intCount As Integer = 4
因为for next
循环不再需要它。
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