vb.net 如何检查Datagridview中的单元格是否有值并继续VB.Net
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How to check if Cell In Datagridview has a value and continue VB.Net
提问by db35m
hi my code is trying to
嗨，我的代码正在尝试
First: Find if value is in a Column 0 "CODE"
Second: If found check if Column 1 "STATUS" has value of "IN" If true MsgBox Appears with Message "Ticket Used" If Value is nothing then Change value to IN
第一：查找值是否在第 0 列“代码”中
第二：如果找到，请检查第 1 列“STATUS”的值是否为“IN” 如果为 true MsgBox 出现消息“Ticket Used” 如果值为空则将值更改为 IN
this is my code:
这是我的代码：
Private Sub changefound()
Dim findtxt As String = txt_Find.Text
Try
If DataGridView2.Rows.Count > 0 Then
For i As Integer = 0 To DataGridView2.Rows.Count - 1
' For j As Integer = 0 To DataGridView2.Columns.Count - 1 'Not using this because we only want to look in CODE column.
Dim CellChange As String = DataGridView2.Rows(i).Cells("CODE").Value.ToString
If CellChange.Contains(findtxt) = True Then
If DataGridView2.Rows(i).Cells("STATUS").Value = "IN" Then 'This is Line 366
MsgBox("Tickets USed")
Exit Sub
Else
With DataGridView2
' .Rows(i).Cells(j).Style.BackColor = Color.Gray
' .Rows(i).Cells(j).Value = findtxt
' MsgBox(i & j + 1)
.Rows(i).Cells("STATUS").Value = "IN"
Exit Sub
End With
End If
End If
'Next 'This is the Jfor
Next
End If
Catch e As Exception
MessageBox.Show(e.ToString())
End Try
End Sub
any way i move it around it will check only if IN is found will it MSGBox used ticket. If cell has no value it locks up with error:
无论我如何移动它，它只会检查是否找到了 IN，它是否会使用 MSGBox 使用的票证。如果单元格没有值，它会锁定错误：
System.InvalidCastException:Operator'=' is not defined for type"DBNull" and string "IN"
At main.vb:line366
System.InvalidCastException:Operator'=' 未为类型“DBNull”和字符串“IN”定义
在 main.vb:line366
any help?
有什么帮助吗？
回答by har07
Add DbNullchecking before doing the comparison :
DbNull在进行比较之前添加检查：
.....
If Not IsDbNull(DataGridView2.Rows(i).Cells("STATUS").Value) _
AndAlso DataGridView2.Rows(i).Cells("STATUS").Value = "IN" Then
.....
Read the following thread for more options to handle DbNulldata :
handling dbnull data in vb.net
阅读以下线程以获取更多处理DbNull数据的选项：
在 vb.net 中处理 dbnull 数据
