使用 OleDbConnection 从数据库中提取数据
Dim con As New OleDb.OleDbConnection
Public outputs As New DataSet
sub main()
sqlquery("SELECT * FROM Students", "mark")
end sub
Sub sqlquery(ByVal sql As String, ByVal outputname As String)
Try
con.Open()
Dim da As OleDb.OleDbDataAdapter
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(outputs, outputname)
con.Close()
Catch
errorid = 3
End Try
Console.WriteLine(messagefromerrorcode)
Console.WriteLine(outputs.Tables(outputname).Rows(0).Item(1))
End Sub
这是我的表格数据和设计的图像
我正在尝试使用 oledb 数据集从数据库中读取一些值，但是当我运行 sql 命令并开始输出值时，我遇到以下错误：“IndexOutOfRangeException：位置 0 处没有行。”。然而，当我在 access 中运行相同的 sql 命令时，我得到了我想要的数据。 当我运行上面的代码时，不会产生任何错误，直到我到达要输出数据的最后一个写入行。
任何想法都会有很大的帮助。
Dim con As New OleDb.OleDbConnection
Public outputs As New DataSet
sub main()
sqlquery("SELECT * FROM Students", "mark")
end sub
Sub sqlquery(ByVal sql As String, ByVal outputname As String)
Try
con.Open()
Dim da As OleDb.OleDbDataAdapter
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(outputs, outputname)
con.Close()
Catch
errorid = 3
End Try
Console.WriteLine(messagefromerrorcode)
Console.WriteLine(outputs.Tables(outputname).Rows(0).Item(1))
End Sub
Here is an image of my table data and design
I am trying to read some values from a database using the oledb dataset however when I run the sql command and get down to outputting the value I am greeted with the following error: "IndexOutOfRangeException: There is no row at position 0.". Yet when I run the very same sql command in access I get back the data I wanted.
When I am running the above code, no errors are produced until I get down to the last writeline where I want to output my data.
Any ideas would be a great help.
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我没有看到任何连接字符串被分配给 OleDbConnection 对象 con。您是否针对此示例编辑了该内容？
这对我来说看起来很混乱，因为 OleDbDataAdapter.Fill 用于在从数据库填充记录集后从记录集中填充数据集。
I don't see any connection string getting assigned to the OleDbConnection object con. Did you edit that out for this example?
This looks messed up to me because OleDbDataAdapter.Fill is for filling a data set from a record set after you have filled ther record set from the database.