vb.net 验证数据表中是否存在列
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/32823164/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Verify if a column exist in a DataTable
提问by Pietro Z.
I need to update an item in a DataTable only if a column exist.
I've tried to write this, but it doesn't work because the column "carta_sistemata" doesn't exist.
仅当存在列时，我才需要更新 DataTable 中的项目。
我试图写这个，但它不起作用，因为“carta_sistemata”列不存在。
If table.Rows(0).Item("column_name") IsNot Nothing Then
TextBox.Text = table.Rows(0).Item("column_name").ToString
End If
Without the "if" the code works, but if the column doesn't exist it throws an exception.
如果没有“if”，代码可以工作，但如果该列不存在，则会引发异常。
TextBox.Text = table.Rows(0).Item("column_name").ToString
回答by codersl
Check column exists before accessing:
在访问之前检查列是否存在：
If table.Columns.Contains("column_name") Then
TextBox.Text = table.Rows(0).Item("column_name").ToString
End If
回答by tezzo
You can use a Try/Catchblock:
您可以使用一个Try/Catch块：
Try
Me.TextBox1.Text = YourDataTableTable.Rows(0).Item("ColumnName").ToString
Catch ex As Exception
End Try
回答by Andrew Mortimer
You can parse through the DataColumn collection on the table and look for the presence of the column you're interested in.
您可以解析表上的 DataColumn 集合并查找您感兴趣的列的存在。
For Each col As DataColumn In table.Columns
If col.ColumnName = "carta_sistemata" Then
'do your update
Exit For
End If
Next
