vb.net 如果 Datagridview 中已经存在，则不要添加值
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Don't Add Value If Already Exists In Datagridview
提问by beginnerVB.Net
I have a "table_info" table with a column for ID,NAME When Adding new ID,Name. I would like to check if it's already exists. and If it exists, produce a MessageBox.
我有一个“table_info”表，当添加新的 ID,Name 时，有一列 ID,NAME。我想检查它是否已经存在。如果存在，则生成一个 MessageBox。
How can this be done
如何才能做到这一点
采纳答案by Justin from Rwanda
Ypu have to refer to use rowCell_IDas string because it is the column name in your datagridivew:
Ypu 必须引用 use rowCell_IDas string 因为它是 datagridivew 中的列名：
Function IsInDatagridview(ByVal cell1 As String, ByVal cell2 As String, ByVal rowCell1_ID As Integer, ByVal rowCell2_ID As Integer, ByRef dgv As DataGridView)
Dim isFound As Boolean = False
For Each rw As DataGridViewRow In dgv.Rows
If rw.Cells("rowCell1_ID" ).Value.ToString = cell1 Then
If rw.Cells("rowCell2_ID" ).Value.ToString = cell2 Then
isFound = True
Return isFound
End If
End If
Next
Return isFound
End Function
回答by STiTCHiCKED
There is more than one way to accomplish this. You could check the datasource/set or the actual datagridview itself, if you don't have too many rows. If it's the later then you could do it like so:
有不止一种方法可以实现这一点。如果您没有太多行，您可以检查数据源/集或实际的 datagridview 本身。如果是后者，那么你可以这样做：
Check Function returned true if the criteria is met:
如果满足条件，检查函数返回真：
Function IsInDatagridview(ByVal cell1 As String, ByVal cell2 As String, ByVal rowCell1_ID As Integer, ByVal rowCell2_ID As Integer, ByRef dgv As DataGridView)
Dim isFound As Boolean = False
For Each rw As DataGridViewRow In dgv.Rows
If rw.Cells(rowCell1_ID ).Value.ToString = cell1 Then
If rw.Cells(rowCell2_ID ).Value.ToString = cell2 Then
isFound = True
Return isFound
End If
End If
Next
Return isFound
End Function
.
.
Then to use the Function to display a MessageBox if the criteria is met:
如果满足条件，则使用函数显示 MessageBox：
If (IsInDatagridview("id", "name", 0, 1, DataGridView1)) Then
''// Code to display message.
MsgBox("Record Exists!", MsgBoxStyle.Information)
End If
You may need to change The ID to an integer but I reckon it should work. Haven't tested it.
您可能需要将 ID 更改为整数，但我认为它应该可以工作。没测试过
Okay so what this will do is iterate through each row 'rw' within the datagridview you specify, checking for String matches of the cell's columns' and if a match is found 'isFound' is set to true then 'isFound' is returned.
好的，这将遍历您指定的 datagridview 中的每一行 'rw'，检查单元格列的字符串匹配，如果找到匹配，则将 'isFound' 设置为 true，然后返回 'isFound'。
