如何以编程方式确定DataColumn的类型? [英] How Do I Programmatically Determine Type of DataColumn?

问题描述

你好！

感谢您阅读我的文章.

我有以下问题:
我的程序包括一个DataGridView，它显示了用户提供的select语句中的数据.我使用OdbcDataAdapter填充数据表，然后将其分配为DataGridView的数据源.

如果用户提供了返回二进制数据的SQL select语句，则当DataGridView尝试显示数据时，我将收到DataError异常.

如何确定数据表中的给定列是否包含二进制数据?我尝试使用DataColumn.DataType，但是无法识别二进制数据(类型为Byte [])(或者我不知道要比较什么).

如果DataGridView在二进制列中显示了二进制数据的字符串表示形式，或仅在列中显示了二进制数据"的消息，那将起作用.

谢谢，

Jess

Howdy!

Thanks for reading my post.

I have the following problem:
My program includes a DataGridView, which shows data from select statements supplied by the user. I use an OdbcDataAdapter to fill a DataTable, which is then assigned as the DataGridView''s DataSource.

If the user supplies an SQL select statement which returns binary data, I get a DataError exception when the DataGridView tries to display the data.

How do I determine if a given column in the datatable includes binary data? I''ve tried using DataColumn.DataType, but binary data (which is of type Byte[]) isn''t recognized (or I don''t know what to compare to).

If the DataGridView showed a string representation of the binary data, or just a message stating ''binary data'' in the column, that would work.

Thanks,

Jess

推荐答案

我能够使用

I was able to use

if (0 == String.Compare(dc.DataType.ToString().Trim(), "System.Byte[]"))

确定数据类型.我将它的表列索引存储在列表中，并且只是删除了该列.


谢谢，

杰西

to determine the datatype. I stored it''s table column index in a list<int>, and just deleted that column.


Thanks,

Jess

List<int> theseAreBinaryData = new List<int>();

foreach (DataColumn dc in dt.Columns)
{
    if (0 == String.Compare(dc.DataType.ToString().Trim(), "System.Byte[]"))
    {
        theseAreBinaryData.Add(dt.Columns.IndexOf(dc.ColumnName));
    }
}
if (theseAreBinaryData.Count > 0)
{
    foreach (int i in theseAreBinaryData)
    {
        dt.Columns.RemoveAt(i);
    }
}
dataGridView.DataSource = dt;

如果对进行 ToString() DataType ，它应该告诉您使用了哪种数据类型，您可以从那里访问.

If you do a ToString() on the DataType, it should tell you what data type is used and you can go from there.

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