vb.net 我从下面的代码中收到错误“位置 0 没有行”
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I am getting Error "There is no row at position 0" from code below
提问by Sibusiso Dlamini
Private Sub Button3_Click (ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
If txtID.Text = "" Then
MsgBox("Please input a valid Employee code to load a corresponding record", MsgBoxStyle.Information)
Else
dbProvider = "Provider=Microsoft.Ace.OLEDB.12.0;"
dbSource = "Data Source = C:\Users\Blessing\Documents\IBCARIP.accdb;Persist Security Info=False"
con.ConnectionString = dbProvider & dbSource
con.Open()
sql = "select * from Calculator where " _
& "EmpCode = " & " '" & txtID.Text & "'"
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "IBCARIP")
lblSAI.Text = ds.Tables("IBCARIP").Rows(inc).Item("SName") & ds.Tables("IBCARIP").Rows(inc).Item("FName")
lblRate.Text = ds.Tables("IBCARIP").Rows(inc).Item("NRate")
lblOT.Text = ds.Tables("IBCARIP").Rows(inc).Item("OTRate")
lblBnk.Text = ds.Tables("IBCARIP").Rows(inc).Item("BName") & ".." & ds.Tables("IBCARIP").Rows(inc).Item("ANumber") & ".." & ds.Tables("IBCARIP").Rows(inc).Item("AType")
con.Close()
ds.Tables("IBCARIP").DataSet.Clear()
MaxRows = ds.Tables("IBCARIP").Rows.Count
'inc = 0
End If
End Sub
The message comes when i enter a wrong or non-existent Employee code in txtID.text
当我在 txtID.text 中输入错误或不存在的员工代码时出现该消息
how can i solve tha problem
我该如何解决这个问题
回答by Dhaval
try as below
尝试如下
you should always check dataset table and rows count
您应该始终检查数据集表和行数
i am not much familiar with vb .net(i am in C#) but i think following is good to go
我对 vb .net 不太熟悉（我在 C# 中）但我认为以下是好的
If txtID.Text = "" Then
MsgBox("Please input a valid Employee code to load a corresponding record", MsgBoxStyle.Information)
Else
dbProvider = "Provider=Microsoft.Ace.OLEDB.12.0;"
dbSource = "Data Source = C:\Users\Blessing\Documents\IBCARIP.accdb;Persist Security Info=False"
con.ConnectionString = dbProvider & dbSource
con.Open()
sql = "select * from Calculator where " _
& "EmpCode = " & " '" & txtID.Text & "'"
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "IBCARIP")
If ds.Tables.Count > 0 AndAlso ds.Tables("IBCARIP").Rows.Count >0 Then
lblSAI.Text = ds.Tables("IBCARIP").Rows(inc).Item("SName") & ds.Tables("IBCARIP").Rows(inc).Item("FName")
lblRate.Text = ds.Tables("IBCARIP").Rows(inc).Item("NRate")
lblOT.Text = ds.Tables("IBCARIP").Rows(inc).Item("OTRate")
lblBnk.Text = ds.Tables("IBCARIP").Rows(inc).Item("BName") & ".." & ds.Tables("IBCARIP").Rows(inc).Item("ANumber") & ".." & ds.Tables("IBCARIP").Rows(inc).Item("AType")
con.Close()
ds.Tables("IBCARIP").DataSet.Clear()
MaxRows = ds.Tables("IBCARIP").Rows.Count
'inc = 0
End if
End If
End Sub
回答by Tim Schmelter
First the most important: you are open for SQL-Injection since you are not using sql-parameters but concatenating the query with user input.
首先最重要的是：您对 SQL 注入开放，因为您没有使用 sql 参数，而是将查询与用户输入连接起来。
The reason for the error is that you are trying to access the a DataRowin the DataTablewithout checking if there is at least one. But you are accessing the row with index inc, maybe the table does not contain so many rows. Why do you use a variable at all here?
错误的原因是您试图访问 aDataRow中的 aDataTable而不检查是否至少有一个。但是您正在访问带有 index 的行inc，也许该表不包含这么多行。你为什么在这里使用一个变量？
da.Fill(ds, "IBCARIP")
If ds.Tables("IBCARIP").Rows.Count = 0 Then Return ' or something else
' here you can safely access the first row...
Here the long version with parameters:
这里是带参数的长版本：
Using con = New OleDbConnection(dbProvider & dbSource)
Dim sql = "select * from Calculator where EmpCode=?"
Using da = New OleDbDataAdapter(sql, con)
da.SelectCommand.Parameters.AddWithValue("@EmpCode", txtID.Text)
da.Fill(ds, "IBCARIP")
If ds.Tables("").Rows.Count > 0 Then
Dim row = ds.Tables("IBCARIP").Rows(0)
Dim SName = row.Field(Of String)("SName")
Dim FName = row.Field(Of String)("FName")
Dim sai = String.Format("{0}{1}", SName, FName)
lblSAI.Text = sai
' ... '
End If
End Using
End Using
